Hydraulically Amplified Self-Healing Electrostatic (HASEL) Pumps

ABSTRACT

A pumping system includes a conduit with an inlet region and an outlet region and a first pump coupled with the conduit between the inlet region and the outlet region. The first pump includes a first actuator chamber configured to house at least a first actuator, a first pump chamber aligned along a longitudinal axis of the conduit, wherein the first pump chamber is in fluid communication with the inlet region and the outlet region, and a first flexible diaphragm separating the first actuator chamber from the first pump chamber. Methods for operating the pumping system are also disclosed.

CLAIM OF PRIORITY

The present application is a national stage entry of PCT ApplicationSer. No. PCT/US20/46494, filed Aug. 14, 2020 and entitled “HydraulicallyAmplified Self-Healing Electrostatic (HASEL) Pumps,” which in turnclaims the benefit of U.S. Provisional Patent Application No.62/886,820, entitled “Hydraulically Amplified Self-Healing Electrostatic(HASEL) Pumps,” filed Aug. 14, 2019. Both aforementioned applicationsare incorporated herein by reference in their entirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

This invention was made with government support under grant number80NSSC18K0962 awarded by NASA. The government has certain rights in theinvention.

FIELD OF THE INVENTION

The present invention relates to soft transducers or actuators and, moreparticularly, to various pumping systems in which one or more types ofhydraulically amplified self-healing electrostatic (HASEL) transducersmay be used.

FIELD OF THE DISCLOSURE

The present disclosure relates to soft transducers or actuators and,more particularly, to various pumping systems in which one or more typesof hydraulically amplified self-healing electrostatic (HASEL)transducers may be used.

SUMMARY OF THE INVENTION

The present disclosure relates to a pumping system including a conduitwith an inlet region and an outlet region and a first pump coupled withthe conduit between the inlet region and the outlet region. The firstpump includes a first actuator chamber configured to house at least afirst actuator, a first pump chamber aligned along a longitudinal axisof the conduit, wherein the first pump chamber is in fluid communicationwith the inlet region and the outlet region, and a first flexiblediaphragm separating the first actuator chamber from the first pumpchamber.

Various other aspects and advantages of the invention will be apparentfrom the following description, figures, and appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The appended drawings illustrate only some implementation and aretherefore not to be considered limiting of scope.

FIGS. 1A-1C illustrate a cross-sectional view of a pumping system havinga flexible electrode which spans a pump chamber, in accordance with anembodiment.

FIGS. 1D-1F illustrate a cross-sectional view of a pumping system havinga flexible electrode which spans a pump chamber and includes baffledinlet and outlet conduits, in accordance with an embodiment.

FIGS. 2A-2C illustrate a cross-sectional view of a pumping system havinga flexible electrode extending longitudinally within a pump chamber, inaccordance with an embodiment.

FIGS. 3A-3C illustrate a cross-sectional view of a pumping system havingat least one actuator chamber and at least one expanding actuatortherein, in accordance with an embodiment.

FIGS. 4A, 4B illustrate a cross-sectional view of a pumping systemhaving a plurality of pumps as described with respect to FIGS. 3A-3C, inaccordance with an embodiment.

FIGS. 5A-5C illustrate a cross-sectional view of a pumping system havingat least one actuator disposed between an outer conduit and a flexiblewall, in accordance with an embodiment.

FIG. 6 illustrates a flow diagram for a method of operating one or morepumps disclosed herein, in accordance with an embodiment.

FIG. 7 illustrates a schematic representation of a pump control system.

FIGS. 8A-8E illustrate a “donut” type HASEL actuator, according to oneembodiment, in accordance with an embodiment.

FIG. 9 illustrates a pull-in transition of the electrodes of a HASELactuator upon an increase in the electrostatic force starting to exceedan increase in mechanical restoring force, causing the electrodes toabruptly pull together, in accordance with an embodiment.

FIGS. 10A, 10B show additional graphical illustrations of the pull-ininstabilities of the donut actuator of FIGS. 8A-8E, in accordance withan embodiment.

FIGS. 11A-11C illustrate a stack of the donut-type actuators of FIGS.8A-8E, in accordance with an embodiment.

FIGS. 12A, 12B illustrate two different shapes for the donut-typeactuators that can exhibit different behaviors because of differentelectrode layouts, in accordance with an embodiment.

FIGS. 13A-13F illustrate an implementation of donut-type HASEL actuatorsthat provides three-dimensional mobility by selectively redistributing aliquid dielectric throughout a ring-shaped deformable shell, inaccordance with an embodiment.

FIG. 14A illustrates an actuation cycle of the donut-type actuator ofFIGS. 8A-8E, in accordance with an embodiment.

FIG. 14B illustrates an experimental setup for measuring theelectromechanical efficiency of the actuator in FIG. 14A, in accordancewith an embodiment.

FIGS. 14C-14I illustrate various electrical measurements for theactuation cycle of FIG. 14A, in accordance with an embodiment.

FIGS. 15A-15C illustrate an exemplary structure of a zipper-type HASELactuator, in accordance with an embodiment.

FIGS. 16A-16C illustrate toroidal zipper-type HASEL actuators, inaccordance with an embodiment.

FIG. 16D illustrates strain recorded per voltage under various loads, inaccordance with an embodiment.

FIGS. 17A-17C illustrate various geometric and mathematicalconsiderations in actuator calculations, in accordance with anembodiment.

FIGS. 18A, 18B illustrate a pumping system using donut-type HASELactuators, in accordance with an embodiment.

FIGS. 19A-19C illustrate a pumping system using linearly contractingHASEL actuators, in accordance with an embodiment.

FIGS. 20A-20D illustrate a pouch-type HASEL actuator in off- andon-states under load, in accordance with an embodiment.

FIG. 21 illustrates modeled data and experimental data relating to theperformance of the actuator in FIGS. 20A-20D, in accordance with anembodiment.

FIGS. 22A-22D illustrate a pumping system using the actuator describedin FIGS. 20A-20D, in accordance with an embodiment.

FIGS. 23A, 23B illustrate a perspective exploded view and across-sectional view, respectively, of the pumping system described withrespect to FIGS. 22A-22D, in accordance with an embodiment.

FIG. 24A illustrates a top down and cross-sectional view of a passivevalve used in the pumping system of FIGS. 22A-22D, in accordance with anembodiment.

FIGS. 24B, 24C illustrate experimental data relating to the passivevalve of FIG. 24A, in accordance with an embodiment.

FIGS. 25A-25H illustrate experimental setups and correspondingexperimental data relating to the performance of the pumping systemdescribed with respect to FIGS. 22A-22D when the system is pumping air,in accordance with an embodiment.

FIGS. 26A-26D an illustrate experimental setup and correspondingexperimental data relating to the performance of the pumping systemdescribed with respect to FIGS. 22A-22D when the system is pumpingliquid, in accordance with an embodiment.

FIG. 27 illustrates a comparison chart of several different types ofpumping systems, in accordance with an embodiment.

FIG. 28 illustrates a graph showing an actuation signal in accordancewith embodiments herein, in accordance with an embodiment.

FIG. 29A illustrates a pumping system that includes the pump describedwith respect to FIGS. 22A-22D, in accordance with an embodiment.

FIGS. 29B, 29C illustrate experimental data related to the pumpingsystem in FIG. 29A, in accordance with an embodiment.

FIGS. 30A-30D illustrate a pumping system having a plurality of distinctelectrodes configured to selectively receive voltage and interact withportions of a flexible electrode to form at least one pocket ofdielectric fluid, in accordance with an embodiment.

FIGS. 31A-31C illustrate a pumping system having a plurality of distinctelectrodes configured to selectively receive voltage and interact withportions of a flexible electrode to form at least one pocket ofdielectric fluid, wherein an opening to the pump chamber is selectivelyopened or closed depending on the location of the pocket, in accordancewith an embodiment.

DETAILED DESCRIPTION

The detailed description set forth below in connection with the appendeddrawings is intended as a description of various configurations and isnot intended to represent the only configurations in which the conceptsdescribed herein may be practiced. The detailed description includesspecific details for the purpose of providing a thorough understandingof various concepts. It will be apparent to those skilled in the artthat these concepts may be practiced without these specific details. Insome instances, well known components are shown in block diagram form inorder to avoid obscuring such concepts.

Hydraulically Amplified Self-Healing Electrostatic (HASEL) Pumps

Pumps are important mechanical devices for a range of applications, andthey are the 2nd most common mechanical device in use behind electricmotors. Pumps act to pressurize and move fluids for applicationsincluding but not limited to heating and cooling, processing or mixingchemicals, hydraulics, and dispensing fluids. Typical pumps are drivenby electric motors and are made from rigid, bulky, and heavy components.As a result, persistent challenges with pumps include reducing noise andvibration, reducing weight, and improving mechanical efficiency.

Nature also makes extensive use of pumps. Passive pumps such as thesap-lifting mechanism of trees extracts nutrients and moisture from thesoil. Active biological pumps, such as the mammalian heart usecontracting muscle chambers and valves to circulate blood throughout thebody. Other examples include hydraulic structures found in arachnidswhich pressurize fluid in various regions of their bodies to generatemotion. These active pumps are driven by the contraction and relaxationof biological muscle—a soft and compliant material. While human-madepumps continue to be improved, in order to take advantage of thebenefits found in nature's pumps, new types of actuators are needed todevelop more life-like pumping systems.

Research into artificial muscles—soft materials which change shape uponstimulation—has sought to replicate the performance and functionality ofbiological muscles. This growing field of research has seen dramaticdevelopments over the past 20 years. Recently introduced HydraulicallyAmplified Self-healing ELectrostatic (HASEL) actuators (see patentapplications “Hydraulically Amplified Self-Healing ElectrostaticActuators” (PCT/US18/023797), and “Hydraulically Amplified Self-HealingElectrostatic Transducers Harnessing Zipping Mechanism”(PCT/US19/020568)) are soft materials capable of performance comparableto natural muscle. HASEL transducers produce mechanical work by applyingelectrostatic forces to structures consisting of a liquid dielectric andsoft or flexible solid dielectric materials. The performance attributesof HASEL transducers make them promising devices for application towardsmechanical systems such as pumps.

Herein, the presented invention describes the use of HASEL actuators invarious embodiments of pumping systems. These pumps are separated into 3distinctly different types: S-shaped HASEL pumps, positive displacementHASEL pumps, and peristaltic HASEL pumps.

S-Shaped HASEL Pumps

FIG. 1A shows the cross section of a basic design for an s-shaped HASELpump.

The hydraulic structure includes three electrodes, two soliddielectrics, and a liquid dielectric separated by one of the electrodes,in the illustrated embodiment. Electrodes #1 and #2 are planar ingeometry and can be constructed from rigid, flexible, or stretchable (orany combination of the three) electrical conductors. Electrode #3 is“S”-shaped (made from a flexible or stretchable electrical conductor)and separated from electrode #1 by a solid dielectric (top dielectric)and separated from electrode #2 by another solid dielectric (bottomdielectric). One end of electrode #3 (in this case the right side) isanchored to the top dielectric with a top support structure, and theother end of electrode #3 (in this case the left side) is anchored tothe bottom dielectric with a bottom support structure. The soliddielectrics and the support structures can be made from rigid, flexible,or stretchable (or any combination of the three) material.

On either side of electrode #3 is a liquid. The liquid dielectric isseparated by electrode #3 such that the liquid on the left and rightside of electrode #3 do not come into direct contact with each other.The liquid dielectric on the left and right side can be the samematerial, or different materials. In this case the hydraulic structurehas an outlet/inlet tube on either side of electrode #3.

The basic operation of the HASEL S-shaped pump device is shown in FIG.1B-C. When a potential difference is applied across electrode #1 and #3,there is an electrostatic force between the two electrodes causing themto move toward each other, FIG. 1B. Since electrode #3 can move freely(other than its anchor points provided by the support structure), itzips to the left along the top dielectric (HASELs with electrostaticzipping mechanisms covered in US provisional patent application(62/638,170) and PCT application (PCT/US2019/020568)). During thisprocess, the liquid dielectric on the left side of electrode #3 ispushed out of the left tube (positive pressure), while the liquiddielectric on the right side of electrode #3 is sucked into the righttube (negative pressure). Once electrode #3 is fully zipped to the left,the potential difference across electrode #1 and #3 is brought to zero(i.e. the capacitor is discharged) and then there is a potentialdifference applied across electrode #2 and #3 (FIG. 1C).

Now, the electrostatic force generated between electrodes #2 and #3causes electrode #3 to zip to the right along the bottom dielectric.Thus, the liquid dielectric on the right side of electrode #3 is pushedout of the right tube (positive pressure) and the liquid dielectric onthe left side of electrode #3 is pulled into the left tube (negativepressure).

The outlet/inlet tubes on the left and right side of the hydraulicstructure can be modified as seen in FIG. 1D, such that each sideincludes two tubes, one for positive pressure and one for negativepressure. The tubes for negative pressure include a check valve thatonly lets fluid flow into the pump, while the tubes for positivepressure include a check valve that only lets fluid flow out of thepump. This design can provide a more continuous flow of fluid, much likea mammalian heart.

This structure illustrated in FIGS. 1A-1F was first proposed as amicroelectromechanical system (MEMs) in the 90's (specifically amicro-switch) and known as an S-shaped actuator. More recently thestructure was shown as an efficient electrocaloric cooling device.However, none of the previous designs was used to pump fluids aspresented here. Additionally, previous versions of the S-shaped actuatordo not utilize the presented structure, that is, one of a HASELactuator.

An advantage of the support structures in FIG. 1 is to allow electrode#3 to zip along either the top or bottom solid dielectrics enabling avariable control of pressure with application of voltage (see HASELswith electrostatic zipping mechanisms covered in provisional patentapplication (62/638,170) and PCT application (PCT/US2019/020568)).However, for some applications, it is advantageous to have a pump thatis more binary, one which is either off or generates a fixed pressurewhen on. FIG. 2 shows a HASEL pump which utilizes a pull-in instabilityfor a pump with a discrete number of stable states.

The structure of this device shown in FIG. 2 is similar to that shown inFIG. 1; however, in this case, electrode #3 has a planar geometry and isparallel to both electrodes #1 and #2. A chamber of liquid dielectricseparates electrode #3 from the top solid dielectric, and a separatechamber of liquid dielectric separates electrode #3 from the bottomsolid dielectric. Each chamber has an inlet and outlet tube. Electrode#3 is constructed from a stretchable or flexible material.

The rest state shown in FIG. 2A is one of the stable states of the pump.When a potential difference is applied across electrodes #1 and #3 thatexceed the mechanical restoring force of the system, electrode #3 isabruptly pulled upwards against the top dielectric. This state isanother stable state of the system, and generates a positive pressure inthe top chamber, and a negative pressure in the bottom chamber, FIG. 2B.

When a potential difference is applied across electrodes #2 and #3 thatexceed the mechanical restoring force of the system, electrode #3 isabruptly pulled downwards against the bottom dielectric. This state isanother stable state of the system, and generates a positive pressure inthe bottom chamber, and a negative pressure in the top chamber, FIG. 2C.Thus, this device has three stable states: off [FIG. 2A], electrode #3pulled upwards [FIG. 2B], or electrode #3 pulled downwards [FIG. 2C].Systems with an alternate number of stable states are possible (i.e. twoor four stable states). Additionally, the inlet/outlet tubes can bedesigned with check valves to control the flow of fluid (as seen in FIG.1D).

Positive Displacement HASEL Pumps

FIG. 3 depicts a HASEL diaphragm pump, in accordance with an embodiment.This design of pump involves stacks of HASEL actuators which act on astretchable diaphragm. The HASEL actuators and diaphragm are mountedwithin a housing. The inlet and outlet of the housing connect to aconduit for transporting the pumped fluid (gas or liquid). One-wayvalves allow for flow only in one direction. When voltage is applied,the HASEL actuators expand to deform the stretchable diaphragm. Thisforces liquid to flow out of the pumping chamber through the one-wayvalve. When voltage is turned off, the elastic force of the membranecauses the HASEL actuators to relax to the initial thickness. As thisoccurs, fluid is drawn into the pumping chamber through the one-wayvalve.

As shown in FIG. 3, this specific type of positive displacement pump(PDP) includes one or more HASEL actuators or stacks of actuators placedwithin a housing. A stretchable or flexible diaphragm is mounted to thehousing (FIG. 3A). The inlet and outlet of the housing connect to aconduit which serves to transport fluid (liquid or gas) through thepump. The inlet of the housing features a one-way valve to allow flow offluid into the pump chamber. The outlet of the housing features aone-way valve to allow flow out of the pump chamber. When voltage isapplied, expansion of the HASEL actuator(s) deform the diaphragm. As aresult, pressure within the pump chamber increases and fluid flowsthrough the outlet (FIG. 3B). Once voltage is turned off, the elasticdiaphragm forces the HASEL actuator(s) to return to their originalposition. This force creates a negative pressure gradient between theinlet and pump chamber and fluid fills the pump chamber.

This pump cycle can be controlled by varying input voltage to the HASELactuator(s). This gives control over volumetric flow rate and pressureof the pump. While one design of HASEL actuators is shown for this pump,a variety of HASEL actuator designs could be applied to create such adiaphragm pump, including actuators that contract on activation (i.e.,Peano-HASELs). The pump can be designed for a range of length scales andflow rates. Both the size of the HASEL actuator(s) and number ofactuators in a stack can be varied to suit the flowrate and pressurerequirements of a specific application.

Capacitive self-sensing can be employed to provide feedback on actuatorposition and force in order to achieve closed-loop pumping. Multipleactuation signals can be superimposed together to achievemultifunctional operation. For example, a low frequency signal can becombined with a high frequency signal to achieve a combination ofpumping and vibratory mixing.

FIG. 4 shows a multiple stage HASEL Diaphragm pump. Much like the humanheart, the HASEL diaphragm pumps can be placed in series with one-wayvalves separating each pump in order to increase the pressure generatedin the pumped fluid. Moving from left to right as shown in FIG. 4, fluidpressure increases at each pump stage so that P1<P2<P3. With a threestage pump, for example, the system alternates between two states whereA) the two outer pumps are activated while the middle is inactive and B)the middle pumps is active while the two outer pumps are inactive.

As shown in FIG. 4, multiple diaphragm pumps can be combined in seriesto increase the pressure output of the pump.

An advantage of this pump design of FIG. 4 is that the pumped fluid isisolated from the high voltage of the HASEL actuators. This enablespumping of fluids that are conductive.

Peristaltic HASEL Pumps

FIG. 5 depicts a HASEL pump which uses peristaltic motion to transportand pressurize a fluid. Fluid (liquid, gas, or granular media) iscontained within an inner conduit. In the embodiment illustrated in FIG.5, HASEL transducers are placed between an inner and outer conduit. Theouter conduit is stiff enough to minimize deflection from force of theHASEL transducer. The inner conduit, which transports the fluid, iselastic and deforms when the HASEL actuates. HASEL actuators arearranged along the length of the conduit and activated sequentially topump the fluid within the inner conduit. A peristaltic wave is createdby activating every other pair of HASEL actuators in sequence, as shownin A-C. This pumping mechanism is similar to peristaltic pumps found innature such as the human esophagus or hearts of many invertebrates.

As shown in FIG. 5, HASEL actuators surround the outer surface of theinner conduit and an outer conduit constrains the HASEL actuators. Theouter conduit may be a rigid or flexible structure. HASEL actuators arearranged along the length of the conduit and activated sequentially topump the fluid within the inner conduit. This pumping mechanism issimilar to peristaltic pumps found in nature such as the human esophagusor hearts of many invertebrates. As depicted in FIG. 5, when activated,the HASEL actuators compress the inner conduit which pressurizes anddisplaces the fluid within. If the wall position at rest is anintermediate actuation state for the actuators, then once the actuatorsare turned off, a distention wave of negative pressure is created thathelps to transport fluid in the direction of the peristaltic wave. Thedepicted sequence shows the peristaltic wave moving from left (FIG. 5A)to right (FIG. 5B). FIG. 5C is the same state as FIG. 5A whichillustrates that this is a continuous and repeating pumping motion.

A benefit of this pump design as shown in FIG. 5 is that no valves oradditional components are required. Direction of flow depends on motionof the peristaltic wave. Fluid flow rate, direction, and pressure can bealtered by changing the order, magnitude, and frequency of the appliedvoltage signal.

Multiple actuation signals can be superimposed together to achievemultifunctional operation. For example, a low frequency signal can becombined with a high frequency signal to achieve a combination ofpumping and vibratory mixing.

A further advantage of the pump design in FIG. 5 is that the pumpedfluid is isolated from the high voltage of the HASEL actuators. Thisenables pumping of fluids that are conductive.

The present invention is described more fully hereinafter with referenceto the accompanying drawings, in which embodiments of the invention areshown. This invention may, however, be embodied in many different formsand should not be construed as limited to the embodiments set forthherein. Rather, these embodiments are provided so that this disclosurewill be thorough and complete, and will fully convey the scope of theinvention to those skilled in the art. In the drawings, the size andrelative sizes of layers and regions may be exaggerated for clarity.Like numbers refer to like elements throughout.

It will be understood that, although the terms first, second, third etc.may be used herein to describe various elements, components, regions,layers and/or sections, these elements, components, regions, layersand/or sections should not be limited by these terms. These terms areonly used to distinguish one element, component, region, layer orsection from another region, layer or section. Thus, a first element,component, region, layer or section discussed below could be termed asecond element, component, region, layer or section without departingfrom the teachings of the present invention.

Spatially relative terms, such as “beneath,” “below,” “lower,” “under,”“above,” “upper,” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. It will beunderstood that the spatially relative terms are intended to encompassdifferent orientations of the device in use or operation in addition tothe orientation depicted in the figures. For example, if the device inthe figures is turned over, elements described as “below” or “beneath”or “under” other elements or features would then be oriented “above” theother elements or features. Thus, the exemplary terms “below” and“under” can encompass both an orientation of above and below. The devicemay be otherwise oriented (rotated 90 degrees or at other orientations)and the spatially relative descriptors used herein interpretedaccordingly. In addition, it will also be understood that when a layeris referred to as being “between” two layers, it can be the only layerbetween the two layers, or one or more intervening layers may also bepresent.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention. Asused herein, the singular forms “a,” “an,” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” when used in this specification, specify thepresence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof. As used herein, the term “and/or”includes any and all combinations of one or more of the associatedlisted items, and may be abbreviated as “/”

It will be understood that when an element or layer is referred to asbeing “on,” “connected to,” “coupled to,” or “adjacent to” anotherelement or layer, it can be directly on, connected, coupled, or adjacentto the other element or layer, or intervening elements or layers may bepresent. In contrast, when an element is referred to as being “directlyon,” “directly connected to,” “directly coupled to,” or “immediatelyadjacent to” another element or layer, there are no intervening elementsor layers present. Likewise, when light is received or provided “from”one element, it can be received or provided directly from that elementor from an intervening element. On the other hand, when light isreceived or provided “directly from” one element, there are nointervening elements present.

Embodiments of the invention are described herein with reference tocross-section illustrations that are schematic illustrations ofidealized embodiments (and intermediate structures) of the invention. Assuch, variations from the shapes of the illustrations as a result, forexample, of manufacturing techniques and/or tolerances, are to beexpected. Thus, embodiments of the invention should not be construed aslimited to the particular shapes of regions illustrated herein but areto include deviations in shapes that result, for example, frommanufacturing. Accordingly, the regions illustrated in the figures areschematic in nature and their shapes are not intended to illustrate theactual shape of a region of a device and are not intended to limit thescope of the invention.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this invention belongs. It will befurther understood that terms, such as those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art and/orthe present specification and will not be interpreted in an idealized oroverly formal sense unless expressly so defined herein.

Referring back to FIG. 1A, a pumping system 100 is shown having a pump102. Pump 102 includes a pump chamber 104 having a first wall 106 and asecond wall 108. Second wall 108 may be substantially opposite the firstwall 106 across the pump chamber 104. First and second walls 106, 108may each be rigid, flexible, or may have both rigid and flexiblesections. A first dielectric 110 is located adjacent the first wall 106.The first dielectric 110 may be a solid or a flexible material and maybe formed from materials such as biaxially oriented polyester film,biaxially oriented polypropylene, polyvinylidene fluoride terpolymer,and polyimide film.

A first electrode 112 is electrically coupled with the first dielectric110. The first electrode is formed from a conductive material that maybe rigid or flexible. In some embodiments, the first electrode 112 isformed from carbon grease, carbon ink, silver ink, conductive fabric, orconductive elastomer.

The pumping system 100 further includes a second electrode 114. Thesecond electrode may be flexible, stretchable, or otherwise movable overat least a portion of its length. In some embodiments, the secondelectrode 114 may be formed from a conductive material such as carbongrease, carbon ink, silver ink, conductive fabric, or conductiveelastomer. The second electrode 114 includes a first end 116 and asecond end 118. First end 116 is coupled with the first wall 106 at afirst support structure 120. The support structure 120 may be formedfrom an insulating material and may be coupled to or integrally formedwith the first wall 106. The second end 118 of the second electrode 114is coupled with the second wall 108 at a second support structure 122.The support structure 122 may be a separate component formed from aninsulating material or may be integrally formed with the second wall108.

The second electrode 114 divides the pump chamber 104 into at least afirst volume 124 and a second volume 126. The first and second volumes124, 126 are shown to be approximately the same size; however, thevolumes can also vary without departing from the scope of the presentdisclosure. The first a second volumes 124, 126 may be filled with firstand second fluids, respectively. The first and second fluids can be thesame fluids or different fluids. In some embodiments, the fluids aredielectric fluids including but not limited to vegetable-basedtransformer oils and silicone-based transformer oils. First and secondconduits 128, 130, respectively, may be fluidly connected with the pump102. More specifically, first conduit 128 may be fluidly connected withfirst volume 124 and second conduit 130 may be fluidly connected withsecond volume 130. FIG. 1A shows the pump 102 in a resting state or anoff-state, which is considered a first stable state.

A power source (not shown) may be electrically coupled with the firstelectrode 112 such that the first electrode is configured to transmit avoltage to the first dielectric 110. When voltage is received by thefirst dielectric 110, a first electric field 132 is generated, as shownin FIG. 1B. In response to the first electric field 132, at least aportion of the second electrode 114 contacts or otherwise moves towardthe first dielectric 110. This position represents a second stable stateof the pumping system 100. In the first stable state, the first volume124 within pump chamber 104 is reduced in size while the second volume126 is increased. Correspondingly, at least a portion of the first fluidmay be pushed out of the pump chamber into the first conduit 128 bypositive pump pressure while at least a portion of the second fluidwhich occupies the second fluid volume 126 and second conduit 130 may bepulled into the pump chamber 104 by negative pump pressure.

Referring to FIGS. 1A and 1C, a second dielectric 134 and a thirdelectrode 136 may be included in pumping system 100. Similar to thefirst dielectric, the second dielectric 134 may be a solid or a flexiblematerial and may be formed from materials such as biaxially orientedpolyester film, biaxially oriented polypropylene, polyvinylidenefluoride terpolymer, and polyimide film. The third electrode 136 isformed from a conductive material that may be rigid or flexible and maybe formed from materials such as carbon grease, carbon ink, silver ink,conductive fabric, and conductive elastomer. The third electrode 136 iselectrically coupled with the second dielectric 134.

A power source (not shown) may be electrically coupled with the thirdelectrode 136 such that the third electrode is configured to transmit avoltage to the second dielectric 134. When voltage is received by thesecond dielectric 134, a second electric field 138 is generated, asshown in FIG. 1C. In response to the second electric field 138, at leasta portion of the second electrode 114 contacts or otherwise moves towardthe second dielectric 134. This position represents a third stable stateof the pumping system 100. In this third stable state, the first volume124 within pump chamber 104 is increased while the second volume 126 isreduced in size. Correspondingly, at least a portion of the second fluidoccupying the second fluid volume 126 may be pushed out of the pumpchamber 104 into the second conduit 130 by positive pump pressure whilethe first fluid occupying the first fluid volume 124 and first conduit128 may be pulled into the pump chamber 104 by negative pump pressure.

When voltage is removed from the system 100, second electrode 114returns to the first stable state due to elasticity of the secondelectrode material and/or due to pressure from the first and secondfluids. The pump 102 can be cycled through the different stable statesin any order.

Referring to FIG. 1D, another embodiment of a pumping system is shown.Pumping system 140 includes the pump 102 fluidly coupled between thefirst conduit 128 and the second conduit 130 as described with respectto FIGS. 1A-1C. A first baffle 142 is included along a portion of thefirst conduit 128 to divide the first conduit into first and secondchannels 144, 146, respectively. A second baffle 148 is included along aportion of the second conduit 130 to divide the second conduit intofirst and second channels 150, 152, respectively. The first and secondbaffles 142, 148 may be positioned away from the pump 102 such thatfirst and second mixing regions 154, 156 are fluidly coupled with thepump 102. One or more of the channels 144, 146, 154, 156 may include acheck valve 158, 160, 162, 164 to control fluid flow into and out of thechannels.

For example, as shown in FIG. 1E, when pump 102 is in the second stablestate and the first fluid is pushed out of pump chamber 104 into thefirst conduit 128, check valve 160 may allow the displaced first fluidto flow into channel 146 while check valve 158 prevents fluid fromentering chamber 144. Correspondingly, as the second fluid is pulledinto pump chamber 104, check valve 162 may allow fluid to flow fromchannel 150 into mixing region 156 and/or pump chamber 104 while checkvalve 164 prevents fluid occupying channel 152 from flowing into themixing region 156.

When pump 102 is in the third stable state, as shown in FIG. 1F, fluidfrom chamber 144 flows through check valve 158 in response to negativepump pressure while fluid in chamber 146 is restrained by check valve160. On the positive pressure side, check valve 164 allows fluid to flowinto channel 152 while check valve 162 remains closed to prevent fluidflow into channel 150.

While two channels per conduit are described, each having a check valvetherein, one of skill in the art will appreciate that more or fewerchannels and check valves may be implemented within the conduits toachieve different fluid flow patterns without departing from the scopeof the present disclosure.

Moreover, while a single pump 102 is shown between the first and secondconduits, additional pumps may be placed in series or in parallel tomodify pumping capacity and provide different fluid flow patterns.

Referring now to FIG. 2A, a pumping system 200 is shown. System 200includes a pump 202 having a pumping chamber 204 defined at least inpart by a first wall 206 and a second wall 208. Second wall 208 may besubstantially opposite the first wall 206 across the pump chamber 204.First and second walls 206, 208 may each be rigid, flexible, or may haveboth rigid and flexible sections. A first dielectric 210 is locatedadjacent the first wall 206. The first dielectric 210 may be a solid ora flexible material and may be formed from materials such as biaxiallyoriented polyester film, biaxially oriented polypropylene,polyvinylidene fluoride terpolymer, and polyimide film.

A first electrode 212 is electrically coupled with the first dielectric210. The first electrode is formed from a conductive material that maybe rigid or flexible. In some embodiments, the first electrode 212 isformed from carbon grease, carbon ink, silver ink, conductive fabric, orconductive elastomer.

The pumping system 200 further includes a second electrode 214. Thesecond electrode may be flexible, stretchable, or otherwise movable overat least a portion of its length. In some embodiments, the secondelectrode 214 may be formed from a conductive material such as carbongrease, carbon ink, silver ink, conductive fabric, or conductiveelastomer. The second electrode 214 includes a first end 216 and asecond end 218. First end 216 is coupled with a first support structure220, which may be formed from an insulating material. The second end 228of the second electrode 214 is coupled with a second support structure222, which may also be formed from an insulating material. In the system200, support structures 220, 222 are part of first and second baffles242, 248 disposed within first and second conduits 228, 230; however,the support structures may be distinct parts coupled with the baffles.In some embodiments, the support structures 220, 222 may lie on alongitudinal axis 254 of pump chamber 204; however, other locations forthe support structures may be selected without departing from the scopeof the present disclosure.

The connections between the second electrode 214 and first and secondsupport structures 220, 222 prevent flow of fluid therethrough and alsoallow for the second electrode to move. The connections may includepivotable, stretchable, bendable, or otherwise flexible attachments. Theresting state shown in FIG. 2A is considered a first stable state forpump 202.

The second electrode 214 divides the pump chamber 204 into at least afirst volume 224 and a second volume 226. The first a second volumes224, 226 may be filled with first and second fluids, respectively. Thefirst and second fluids can be the same fluids or different fluids. Insome embodiments, the fluids are dielectric fluids including but notlimited to vegetable-based transformer oils and silicone-basedtransformer oils. While first and second volumes 224, 226 are shown tobe approximately the same size, dimensions of the first and secondvolumes may be the same or different and are selectable based on thefluids to be pumped as well as desired flow rates, pressures, and thelike. In some embodiments, the pump 202 may include only a single volumewhere the second electrode 214 acts as the second wall 208. In otherembodiments, the pump 202 may include first and second volumes, wherefluid occupying the first volume is a dielectric fluid as discussedabove and the fluid occupying the second volume is any fluid, such as agas or liquid, and may have conductive or poorly insulating properties.

The first and second conduits 228, 230, respectively, may be fluidlyconnected with the pump 202. The first baffle 242 divides the firstconduit 228 into first and second channels 244, 246. The second baffle248 divides the second conduit 230 into first and second channels 250,252. Together with the second electrode 214, the first and secondbaffles 242, 248 may prevent the first fluid from mixing with the secondfluid. Additionally, the configuration shown in system 200 allows forfluid communication between channel 244, second volume 226, and channel252. Similarly, channel 246, first volume 224, and channel 250 are influid communication.

Operation of the pump 202 is discussed with reference to FIGS. 2A-C. InFIG. 2B, a voltage is applied to the first dielectric 210 from a powersource (not shown) via the first electrode 212. When the voltage isreceived by the first dielectric 210, a first electric field 232 isgenerated. In response to the first electric field 232, at least aportion of the second electrode 214 contacts or otherwise moves towardthe first dielectric 210. This position represents a second stable stateof the pumping system 200. In the second stable state, the first volume224 within pump chamber 204 is reduced in size while the second volume226 is increased. Correspondingly, at least a portion of the first fluidis displaced from the pump chamber 204 and into channels 246, 250 of thefirst and second conduits 228, 230, respectively, by positive pumppressure. At the same time, at least a portion of the second fluid,which occupies the second fluid volume 226 and channels 244, 252 offirst and second conduits 228, 230, is pulled into the pump chamber 204by negative pump pressure.

Referring to FIGS. 2A and 2C, a second dielectric 234 and a thirdelectrode 236 may be included in pumping system 200. Similar to thefirst dielectric, the second dielectric may be a solid or a flexiblematerial and may be formed from materials such as biaxially orientedpolyester film, biaxially oriented polypropylene, polyvinylidenefluoride terpolymer, and polyimide film. The third electrode 236 isformed from a conductive material that may be rigid or flexible and maybe formed from materials such as carbon grease, carbon ink, silver ink,conductive fabric, and conductive elastomer. The third electrode 236 iselectrically coupled with the second dielectric 234.

A power source (not shown) may be electrically coupled with the thirdelectrode 236 such that the third electrode is configured to transmit avoltage to the second dielectric 234. When voltage is received by thesecond dielectric 234, a second electric field 238 is generated, asshown in FIG. 2C. In response to the second electric field 238, at leasta portion of the second electrode 214 contacts or otherwise moves towardthe second dielectric 234. This position represents a third stable stateof the pumping system 200. In this third stable state, the first volume224 within pump chamber 204 is increased while the second volume 226 isreduced in size. Correspondingly, at least a portion of the second fluidoccupying the second fluid volume 226 may be pushed out of the pumpchamber 204 into channels 244, 252 within the first and second conduits228, 230, respectively, by positive pump pressure. The first fluid,which occupies the first fluid volume 224 and channels 246, 250 withinthe first and second conduits 228, 230, is pulled into the pump chamber204 by negative pump pressure.

Pumps 102 and 202 may have different pumping characteristics due totheir different configurations. For example, when a voltage is appliedto one of the dielectrics included in pump 102, the second electrode 114may gradually attract to the generated electric field along the lengthof the second electrode 114 in a “zipping” type response. The zippingmechanism will be discussed in further detail below. In contrast, thesecond electrode 214 of pump 202 may have a more immediate response whenmoving between stable states. Thus, the pump 202 may more closelyapproximate a binary on/off response than pump 102.

The response of pumps 102 and 202 may also be tuned by adjusting one ormore variables of the input signal. For example, frequency, amplitude,polarity, offset and other signal characteristics may be adjusted. Insome embodiments, a control module may be coupled with the power sourceto monitor and/or adjust the actuation signal received by the variouspumping systems.

Referring to FIG. 6, a process flow chart is shown outlining a method600 for operating pumping systems 100 and 200. The method 600 includesproviding a first fluid in a first fluid volume of a pump chamber (step602) and providing a second fluid in a second fluid volume of the pumpchamber, the first volume separated from the second volume by a movableelectrode (step 604). A first dielectric is provided adjacent a firstside of the pump chamber (step 606). At a first time, a first electricfield is generated by applying a first voltage to the first dielectric(step 608). At least a portion of the movable electrode is moved towardthe first dielectric in response to the first electric field (step 610),thereby applying positive pressure to the first fluid in the firstvolume (step 612) and applying negative pressure to the second fluid inthe second volume (614). The method may further include providing asecond dielectric adjacent a second side of the pump chamber (step 616)and, at a second time, generating a second electric field by applying asecond voltage to the second dielectric (step 618). At least a portionof the movable electrode is moved toward the second dielectric inresponse to the second electric field (step 620), thereby applyingnegative pressure to the first fluid in the first volume (step 622) andapplying positive pressure to the second fluid in the second volume(step 624).

Alternative methods of operating pumping system 100 and 200 arepossible. For example, pumps 102 and 202 may be alternated between anyof the first, second, and third stable states as desired. Pumps 102, 202may also by operated by generating only one electric field with a singledielectric rather than generating two electric fields with twodielectrics. In such a configuration, the pumps 102, 202 may alternatebetween first and second or first and third stable states only. Methodsof operating the pumps may also include generating and holding anelectric field such that the pumps 102, 202 maintain a single positionfor an extended duration of time. One or more of frequencies,amplitudes, and signal profiles of the input signal may be adjusted totune the pump response, fluid flow characteristics, and fluid pressures.

FIG. 7 shows a schematic drawing of a control module 702 operativelycoupled with a power source 704. The power source 704 is coupled withpumping system 706. The control module 702 may send a signal 708instructing power source 704 to provide an actuation signal 710 to thepumping system 706. Variation in the actuation signal 710 may bedetected at monitoring signal 712 which may provide information aboutpressures, flow rates, or other conditions within the pumping system.The monitoring signal may be relayed back to the control module 702through feedback signal 714. The control module may be configured tocalculate a new instruction signal 708 based on the feedback signal 714.Thus, a closed-loop feedback mechanism may be used to monitor andoperate pumping systems disclosed herein.

Referring back to FIGS. 3A-3C, a pumping system 300 is shown, inaccordance with another embodiment. Pumping system 300 includes a pump302 having a pump chamber 304. Pump chamber 304 is in fluidcommunication with one or more sections of conduit, for example an inletconduit 328 and an outlet conduit 330. The pump chamber 304 is definedby a first wall 306 and a second wall 308; the second wall 308 may besubstantially opposite the first wall 306 across pump chamber 304. Thepump chamber may be aligned along a longitudinal axis 354 of one or moreof inlet conduit 328 and outlet conduit 330.

Pump 302 further includes at least one actuator chamber 310 configuredto house at least one actuator 312. The actuator chamber 310 may beseparated from pump chamber 304 by the first wall 306. The first wall306 may be a flexible diaphragm formed from a bendable and/orstretchable material, such as an elastomer, that is impermeable to fluiddisposed within the conduits 328, 330 and pump chamber 304. Inembodiments having a single actuator chamber 310, wall 308 may be arigid wall. Alternatively, in configurations where a second actuatorchamber 334 is included in pump 302, the wall 308 may be a flexiblediaphragm formed from a bendable and/or stretchable material that isimpermeable to fluid disposed within the conduits 328, 330 and pumpchamber 304. The second actuator chamber 334 may house one or moreadditional actuators 312.

The actuators 312 may be hydraulically amplified self-healingelectrostatic (“HASEL”) transducers, which are described in furtherdetail herein with reference to FIGS. 8A-21. Specifically, the actuators312 may be similar to the donut-type HASEL actuators 2200 discussed withreference to FIGS. 8A-14I or zipper-type HASEL actuators discussed withreference to FIGS. 15A-16D. Multiple actuators 312 may be stackedtogether in order to adjust and tune the action of the pump.

Expanding type actuators are shown in FIGS. 3A-3C. The actuators 312 areconsidered expanding type actuators because they increase in height(i.e., in the y-direction) when a voltage is applied. The expandingactuator, or stack of expanding actuators, has a first height 314 in anoff-state when no voltage is applied to the system. The pump chamber hasa corresponding first height 316 associated with the off-state. Thefirst height 316 of the pump chamber may be adjusted by adjusting alocation or first height 314 of the actuators. This may be done byvarying the size, type, and/or number of actuators 312 in the actuatorchamber 310 or by varying one or more dimensions of the actuator chamber310 itself. For example, an actuator chamber with a smaller height inthe y-direction and/or more actuators located therein may push wall 306toward pump chamber 304 and may reduce the first height 316 and/or firstvolume of the pump chamber compared to a pump which includes an actuatorchamber with a larger height in the y-direction and/or fewer actuators.A system with a larger actuator chamber and/or fewer actuators may pullwall 306 away from pump chamber 304 thereby increasing the first height316 and/or first volume of the pump chamber. Many design variationsrelating to dimensions, arrangements, and numbers of actuators arepossible without departing from the scope of the present disclosure.

While FIGS. 3A-3C show a first stack of four actuators in the firstactuator chamber 310 and a second stack of four actuators in the secondactuator chamber 334, any number of actuators may be used. The number ofactuators in the first chamber can be the same as or different from thenumber of actuators in the second chamber. For example, the secondactuator chamber may include more or fewer actuators than first actuatorchamber. The number of actuators used may depend in part upon the firstheight 316 of pump chamber 304. For example, it may be desirable toinclude enough actuators within the one or more of the actuator chambers310, 334 that the actuators are able to expand into and completely closeoff the pump chamber 304 as shown in FIG. 3B.

The pumping system 300 may include one or more valves 318, 320 tocontrol fluid flow. The valves 318, 320 may be check valves or one-wayvalves that allow flow in a first direction (e.g., to the right in FIGS.3A-3C) while preventing fluid flow in a second direction substantiallyopposite the first direction (e.g., to the left). One or more of thevalves 318, 320 may be disposed within the pump 302 and/or within theinlet and outlet conduits 328, 330.

Referring now to FIG. 3B, pumping system 300 is shown in an on-state. Avoltage is applied to the actuators 312 by one or more power sources(not shown). The power source may be modulated by a control unit (notshown) that provides instructions to the power source relating to theactuation signal.

As discussed above, the actuators 312 are expanding actuators and thusthe second height 322 of the actuator stack is larger than the firstheight 314. The actuators 312 push first wall 306 at least partiallyinto the pump chamber. In the embodiment shown, a second actuatorchamber 334 is similarly actuated by the same or a different powersource such that the second wall 308 is simultaneously pushed at leastpartially into the pump chamber. The height of the pump chamber isreduced and, as shown in FIG. 3B, can be decreased to zero by bringingthe first and second walls 306, 308 into contact. As the pump chamberheight collapses, the fluid occupying the pump chamber is pressurizedand displaced from the pump chamber.

Check valves 318, 320 may control the flow of the displaced fluid. Asshown in FIG. 3B, the first check valve 318 remains closed to preventfluid from entering the inlet conduit 328 from the pump chamber. Thesecond check valve 320 opens in response to the fluid pressure and fluidis allowed to flow therethrough into outlet conduit 330.

Fluid within conduits 328, 330 and pump chamber 304 can be any fluid andcan be in liquid of gaseous form. In some embodiments, the fluid can beelectrically conductive.

Referring to FIG. 3C, pump 302 returns to an off-state by reducing orremoving voltage from the system 300. Expanding actuators 312 relax anddecrease in height from second height 322 to the first height 314.Correspondingly, the height of pump chamber 304 increases from zero tothe first height 316. As the height and volume of pump chamber 304increase, a negative pressure is created within the pump chamber 304.The second valve 320 may pull closed in response to the negativepressure, thereby preventing fluid from the outlet conduit 330 fromentering the pump chamber 304. The first valve 318 may open in responseto the negative pressure, thereby allowing fluid from the inlet conduit328 to flow through into the pump chamber 304. The pump 302 can becycled through on- and off-states to continue moving fluid therethrough.

In some embodiments, the pump 302 can be operated as a variable valve.For example, the actuators may receive a voltage and expand to such thatthe height of pump chamber 304 is reduced to a non-zero dimension. Thepump may be held in this intermediate state to restrict flow or tocontrol pressure of fluid moving therethrough. Flow sensors or pressuresensors may be positioned downstream and or upstream of the pump 302 andmay provide feedback to a control module. The control module may comparethe real-time data to a target flow rate or pressure and calculate a newpump position based on the real-time data.

In some embodiments, the actuators may expand such that the height ofthe pump chamber 304 is reduced to zero, thereby closing off fluidcommunication between the inlet conduit 328 and outlet conduit 330. Manyvariations on the method of operating pumping system 300 may be used tocontrol various flow and pressure properties of the fluid therein.

Referring now to FIGS. 4A and 4B, a pumping system 400 is shown havingseveral pumps 302 a, 302 b, 302 c (FIGS. 3A-3C) connected, eitherdirectly or indirectly, in series between an inlet conduit 428 and anoutlet conduit 430. Pump chambers 304 a, 304 b, and 304 c may be inselective fluid communication with each other and with inlet and outletconduits 428, 430. The pump chambers may be aligned along a longitudinalaxis 454 as shown. Each of pumps 302 a, 302 b, and 302 c include atleast a first actuator chamber 310 a, 310 b, 310 c which houses anexpanding actuator 312 or a stack of expanding actuators. The pumps mayfurther include a second actuator chamber 334 a, 334 b, 334 c whichhouses at least one expanding actuator 312. First actuator chambers areseparated from the pump chambers by a first wall 306 a, 306 b, 306 c.Second actuator chambers are disposed substantially opposite the firstactuator chambers and are separated from the pump chamber by secondwalls 308 a, 308 b, 308 c.

As discussed with respect to FIGS. 3A-3C, actuators 312 are expandingactuators having an initial height 314 a, 314 b, 314 c in they-direction when in an off-state and no voltage is applied to theactuators. When a voltage is applied, the height of the actuatorsincreases to a second height 322 a, 322 b, 322 c, thereby pushing firstwalls 306 a, 306 b, 306 c and/or second walls 308 a, 308 b, 308 c intopump chambers 304 a, 304 b, 304 c, respectively. One or more checkvalves 418, 420, 422, 424 can be included within system 400 to controlfluid flow. It may be advantageous to include a check valve between eachpump with all of the valves oriented to allow fluid flow in the samedirection (i.e., toward the right in FIGS. 4A, 4B).

When multiple pumps are connected in series, operation of the multiplepumps can be varied over time to control fluid flow and pressure. Forexample, as shown in FIG. 4A, pumping system 400 can be operated suchthat pumps 302 a, 302 c are in the same state at the same time (i.e., anon-state in FIG. 4A and an off-state in FIG. 4B) while pump 302 b is ina different state (i.e., an off-state in FIG. 4A and an on-state in FIG.4B). Such a method of alternating the states of adjacent pumps mayassist flow of fluid through the pumping system.

In some embodiments, fluid enters pump chamber 304 a at a first pressureP₁ when pump 302 a is in an off state (FIG. 4B). When the pump 302 aactuates, fluid from pump chamber 304 a is pushed through open checkvalve 420 into pump chamber 304 b due to positive pressure from pump 302a and/or negative pressure within pump 302 b. The fluid occupies pumpchamber 304 b and has a second pressure P₂ which may be greater than thefirst pressure P₁. When pump 302 b actuates, the fluid is displaced frompump chamber 304 b through open check valve 422 and into pump chamber304 c due to positive pressure from pump 302 b and/or negative pressurewithin pump 302 c. The fluid now occupies pump chamber 304 c and has athird pressure P₃ which may be greater than or equal to P₂. Similarly,pump 302 c actuates to displace the fluid from pump chamber 304 cthrough open check valve 424 and into the outlet conduit 430 at apressure P₄ which may be greater than or equal to pressure P₃.Additional pumps may be added to the pumping system 400 to furthermodify the pressure of fluid flowing therethrough.

While the operation of FIGS. 4A and 4B show adjacent pumps positioned inopposite states (i.e., on, off, on or off, on, off), other operationalschemes are possible. For example, one or more of the pumps can bepositioned at one or more intermediate state that exists in betweenfully on- and off-states. For example, at a given time, first pump 302 acan be positioned at an intermediate state between on and off such thatpump chamber 304 a has a height between zero and first height 316 a.Simultaneously, second pump 302 b can be positioned in an on-state tofully close the pump chamber 304 b, and third pump 302 c can bepositioned in an off-state to fully open pump chamber 304 c. By varyingthe timing of pump actuation, fluid pressure and flow characteristicsthrough the pumping system can be adjusted.

In some embodiments, actuators 312 are tilting actuators that can beasymmetrically actuated such that a first side of the actuator increasesin height more than a second side when voltage is applied. This conceptis discussed in detail with respect to FIGS. 13A-13F. Using a tiltingactuator may provide further control of the motion and pressure of fluidmoving through pumping system 400 by allowing each pump to exist at morethan one state at a given time. For example, the first side of theactuator may be in an intermediate state while the second side is in afully on- or off-state. In other examples, the first and second sides ofthe actuator may exist at different intermediate states. Such anactuator may be particularly useful in achieving peristaltic fluidmovement as it can gradually push fluid through the pumping systemwithout abrupt changes in pressure.

Using tilt actuation methods may also provide an alternative to usingcheck valve components in the system 400. At a first time, a first sideof the actuator nearest a fluid inlet can be actuated to a fullyon-state, thereby closing off the fluid channel that leads to the inletconduit 428, for example, while the second side remains in an off- orintermediate-state to allow fluid flow. At a second time, the secondside of the actuator can be actuated to decrease the height of the pumpchamber and displace fluid toward the outlet conduit while the firstside remains fully on.

In some embodiments, actuators 312 may be similar to the actuators 2000shown in FIGS. 20A-20D. Actuators 2000 are discussed in detail hereinbelow.

FIGS. 5A-5C show a pumping system 500. The system 500 includes aplurality of pumps 502 a, 502 b, 502 c, 502 b disposed in series andwithin an outer conduit 510. Outer conduit 510 may be formed from arigid or semi-rigid material. A first flexible wall 506 and a secondflexible wall 508 define a fluid channel within the outer conduit 510.The plurality of pumps includes actuators 512 located in a space betweenthe outer conduit and the first and second flexible walls 506, 508.Specifically, each pump may include a first actuator 512 between theouter conduit 510 and the first flexible wall 506 and/or a secondactuator 512 between the outer conduit 510 and the second flexible wall508. The actuators 512 may be expandable actuators configured toincrease in height in the y-direction when a voltage is applied.Specifically, actuators 512 may be donut-type HASEL actuators which canbe actuated uniformly for even height change across the actuator orasymmetrically to tilt the actuators. Tilt actuation is furtherdescribed with respect to FIGS. 13A-13F below. Alternatively, theactuators 512 may be formed as individual pouches similar to the HASELactuators discussed with respect to FIGS. 20A-20D below.

During operation of pumping system 500, voltage may be applied to one ormore pumps at a given time. In some embodiments, adjacent pumps may beactuated such that they are in opposite states (e.g., at a given time,pump 502 a is on, pump 502 b is off, pump 502 c is on, pump 502 d isoff); however, other methods of operating the pumps are possible. Forexample, pumps can be actuated to intermediate-states between fully on-and off-states to accomplish a smooth peristaltic pumping action. Asdiscussed with respect to FIGS. 4A-4C, fluid pressure can increase instages across the pumping system 500. For example, fluid may enter afirst pump chamber 504 a at a first pressure P₁ (FIG. 5B). Actuation ofpump 502 a may push the fluid into second pump chamber 504 b at a secondpressure P₂ which may be greater than P₁ (FIG. 5C). Actuation of pump502 b may push the fluid into third pump chamber 504 c at a thirdpressure P₃ which may be greater than second pressure P₂ (FIG. 5B).Actuation of pump 502 c may push the fluid into fourth pump chamber 504d at a fourth pressure P₄ which may be greater than third pressure P₃(FIG. 5C). Finally, actuation of pump 502 d may push the fluid into anoutlet conduit or a subsequent pump chamber at a pressure P₅ which maybe greater than P₄ (FIG. 5B). The various pressures achieved throughpumping system 500 may depend in part on the size and types ofactuators, the size of pump chambers, and the actuation signal used tooperate the actuators.

FIGS. 5A-5C show operation of pumping system 500 using uniform actuationof actuators 512; however, as discussed above, tilting actuation methodsmay be used instead of or in addition to the uniform actuation. Usingtilting actuators may improve efficiency of fluid flow in systems thatdo not include check valves. At a first time, a first side of thetilting actuator can be actuated to a fully on-state such that fluidflow in a first direction is substantially prevented. While the firstside remains fully on to prevent fluid flow, the second side can beactuated to an intermediate or fully on state to gradually push thefluid in a second direction which may be opposite the first direction.Timing of actuation of the plurality of pumps may be selected such thatactuators, or sides of actuators, that are adjacent each other achieve afully on-state in succession to push fluid through pumping system 500 ina peristaltic motion.

Turning to FIGS. 8A-8E, a specific type of HASEL actuator in the form ofa donut-type HASEL actuator 2200 is shown to illustrate conversion ofelectrical actuation to mechanical deformation. The donut-type actuator2200 includes a flexible shell or pouch 2208 (e.g., elasticallydeformable) that defines an enclosed internal cavity 2209, a liquiddielectric 2212 contained within the enclosed internal cavity 2209, afirst electrode 2216 disposed over a first side (not labeled) of theenclosed internal cavity 2209, and a second electrode 2217 disposed overan opposite second side (not labeled) of the enclosed internal cavity2209. For instance, the first and second electrodes 2216, 2217 mayinclude respective first and second electrical leads 2221, 2223 to whicha voltage (e.g., DC voltage) is configured to be applied. While thefirst and second electrodes 2216, 2217 are illustrated as being disposedon or over an outer surface (not labeled) of the shell 2208 (e.g., thefirst electrode 2216 being disposed over an upper or a first outersurface and the second electrode 2217 being disposed over a lower or asecond outer surface), other embodiments envision that the first andsecond electrodes 2216, 2217 could be disposed on or over an innersurface (not labeled) of the shell 2208 (e.g., such that the first andsecond electrodes 2216, 2217 are in direct contact with the liquiddielectric 2212). In a further embodiment, one of the first and secondelectrodes 2216, 2217 may be disposed over an inner surface of the shell2208 (e.g., on the inside of the internal cavity 2209) and the other ofthe first and second electrodes 2216, 2217 may be disposed over an outersurface of the shell 2208 (e.g., outside of the internal cavity 2209).Regardless of whether the first and second electrodes 2216, 2217 aredisposed inside or outside of the internal cavity 2209, the firstelectrode 2216 may be considered disposed over a first side of theinternal cavity 2209 and the second electrode 2217 may be considereddisposed over a second side of the internal cavity 2209.

A surface area of the shell 2208 over which the first and secondelectrodes 2216, 2217 are disposed comprises an active area 2224 of theshell 2208 and a surface area of the shell 208 over which the first andsecond electrodes 2216, 2217 are not disposed comprises an inactive area2228 of the deformable shell. While the active area 2224 may besurrounded by the inactive area 2228 as illustrated in the figures,other embodiments envision that the inactive area 2228 may be surroundedby the active area 2224. In any case, application of a voltage to oracross the first and second electrodes 2216, 2217 (e.g., via therespective first and second electrical leads 2221, 2223) induces anelectric field through the liquid dielectric 2212 (e.g., and shell 2208)to generate electrostatic forces that attract the first and secondelectrodes 2216, 2217 (where such electrostatic forces generally extendalong a first reference axis 2250). The generated electrostatic forcesgenerate an electrostatic Maxwell stress on the active area 2224 of theshell 2204. Compare FIGS. 8A-8B. The electrostatic stress displaces theliquid dielectric 2212 in the active area 2224, thus generatinghydrostatic pressure that acts on the shell 2208 (e.g., in the inactivearea 2228) to urge the shell in one or more different directions so asto move the shell 2208, stretch the shell 2208, etc.

Stated differently, applying a voltage (e.g., high-voltage signal)across the electrodes 2216, 2217 generates an electrostatic force thatcauses the electrodes 2216, 2217 to attract or otherwise draw together,where the attraction displaces the liquid dielectric 2212 in between theelectrodes 2216, 2217 along a second reference axis 2254 from the activearea 2224 into the inactive area 2228, thus coupling electrostaticstress to fluidic pressure. The pressurized liquid dielectric 2212 candeform (e.g., flex) the shell 2208 (e.g., in the inactive area 2228 inthis embodiment) to perform mechanical work, such as lifting a load. Forinstance, the pressurized liquid dielectric 2212 can, upon being forcedinto the inactive area 2228, urge against the shell 2208 to elasticallydeform the shell 2208 in the inactive area 2228, such as along a thirdreference axis 2258 that is parallel to the first reference axis 2250.Compare shape of inactive area 2228 in FIGS. 8A, 8B, and 8D and also inFIGS. 8C and 8E. For instance, note how a thickness of the inactive area2228 increases while a thickness of the active area 2224 decreases thuscreating “out-of-plane” deformation of the structure. In onearrangement, the shell 2208 may be inhibited from elastic deformationalong at least a portion of the second reference axis 2254 in anyappropriate manner. For instance, note how the overall width of theactuator 2200 remains constant in FIGS. 8A, 8B, and 8D.

As illustrated, the actuator 2200 can take a toroidal, or any othersuitable shape. The ratio of the active area 2224 to inactive area 2228can be adjusted for scaling force and strain according to hydraulicprinciples. It can be seen that as the applied voltage increases from V₁to V₂, there is a small increase in actuation strains. Compare FIGS. 8Aand 14B. However, when the voltage surpasses a threshold V₂ andincreases to V₃ for instance, the increase in electrostatic force startsto exceed the increase in mechanical restoring force (e.g., owing to theelasticity of the shell 2208 and/or a load being applied to the shell2208), causing the first and second electrodes 2161, 2162 to abruptlypull together (see FIGS. 8D and 9); this is a characteristic feature ofa so-called pull-in or snap-through transition. Pull-in transitions andother nonlinear behaviors are features of soft active systems that offeropportunities to improve actuation response or functionality and havebeen used to amplify the response of fluidic and dielectric elastomer(DE) actuators. After the pull-in transition, actuation strain furtherincreases with voltage; this describes the pull-in instability that isshown in FIG. 9. Experimental data in FIGS. 10A and 10B reflects thisbehavior (e.g., that actuation strain is small until a sudden increasein strain occurs after a certain threshold).

FIGS. 10A-10B further illustrate hydraulic behaviors of HASEL actuatorssuch as the donut-type actuators 2200 described in relation to FIGS.8A-8E. For the sake of illustration, two donut-type HASEL actuators 2200are shown in FIGS. 10A-10B, respectively, as fabricated with identicalelastomeric shells and volume of liquid dielectric, but with differentelectrode areas relative to the diameter of the pouch (the shells,liquid dielectric, and electrodes not labeled in the interest ofclarity). As shown, varying the electrode area in this way can tune thestrain and force of actuation. FIG. 10A shows linear strain as afunction of applied voltage under various loads for a first donut-typeHASEL actuator with an electrode diameter of 2.5 cm. This actuatorachieves relatively large strains but generates relatively low force.FIG. 10B shows linear strain as a function of applied voltage undervarious loads for a donut-type HASEL actuator with 1.5 cm diameterelectrodes. This actuator generates relatively large forces but achievesrelatively low strains. In both cases, an electromechanical pull-ininstability can be observed, as indicated by a sudden jump in linearstrain. This pull-in instability can be harnessed to create unique modesof nonlinear actuation in certain implementations.

Different performance characteristics of the donut-type HASEL actuators2200 can be altered by varying the arrangement of the actuators 2200,arrangement of the electrodes 2216, geometry, material, and/or thicknessof the shell 2208, volume of liquid dielectric 2212 inside the shell2208, and/or other parameters. For example, the shell 2208 can be madeout of elastomers or flexible plastics to achieve specific actuationresponses, and the frequency response of the actuator 2200 can varydepending on the viscosity of the liquid dielectric 2212, the overallsize of the actuator 2200, etc. As one example, FIGS. 11A-11C show thatthe overall stroke of actuation can be increased by stacking donut-typeHASEL actuators 2200 to create a stack 2300. Specifically, FIGS. 11A-11Cshow the relaxed state (without an applied voltage in FIG. 11A) and anactivated state (with an applied voltage in FIGS. 11B-11C) of a stack2300 of five donut-type HASEL actuators 2200. As shown, the active areas2224 of adjacent actuators 2200 in the stack 2300 may overlap and theinactive areas 2228 of adjacent actuators 2200 in the stack 2300 mayoverlap. In other embodiments, however, active and inactive areas 2224,2228 of adjacent actuators 2200 in the stack 2300 may overlap orpartially overlap.

In one arrangement, all of the first electrodes 2216 may be electricallyinterconnected in parallel and all of the second actuators 2217 may beelectrically interconnected in parallel. In another arrangement, all ofthe first electrodes 2216 may be electrically interconnected in seriesand all of the second actuators 2217 may be electrically interconnectedin series. In one arrangement having a stack of five donut-type HASELactuators, each with an electrode diameter of 2.5 cm, the stack achieved37% linear strain, which is comparable to linear strain achieved bybiological muscle and corresponds to an actuation stroke of 7 mm (FIG.8B). Hydraulic pressure is generated locally in each donut-typeactuators 2200, and liquid dielectrics 2212 (not labeled) are displacedover short distances, allowing for high-speed actuation. The stackedactuators readily showed large actuation response up to a frequency ofat least 20 Hz. While not illustrated, one or more objects could bedisposed on top of the stack 2300 and moved upwardly and downwardly uponapplication of a voltage to the stack 2300 and removal of the voltagefrom the stack 2300.

As another example of impacting performance of the actuators by alteringparameters, FIGS. 12A-12B illustrate two different shapes for donut-typeHASEL actuators 2200 that can exhibit different behaviors because ofdifferent electrode layouts. In particular, FIG. 12A shows anillustrative donut-type HASEL actuator 2200′ with an asterisk-shapedelectrode layout both without and with an applied voltage while FIG. 12Bshows an illustrative donut type HASEL actuator 2200″ with anannulus-shaped electrode layout both without and with an appliedvoltage. In FIG. 12B, it can be seen how the active area 2224″ may besurrounded by one portion of the inactive area 2228″ while anotherportion of the inactive area 2228″ may be surrounded by the active area2224″.

As another example of impacting performance of the actuators by alteringparameters, FIGS. 13A-13F illustrate an implementation of a donut-typeHASEL actuator 2200′ that can provide three-dimensional mobility. Theillustrated donut-type HASEL actuator 2200′″ is configured toselectively redistribute a liquid dielectric 2212′ throughout aring-shaped deformable shell 2208′″, thereby conferringthree-dimensional mobility to the actuator 2200′″. The ring-shapedvolume of liquid dielectric 2212 may be surrounded by an insulatingskirt 2211′″, with opposing electrode pairs (e.g., 2216 ₁′″/2217 ₁′″,etc.) spaced along the surface of the shell to create a plurality ofactive areas 2224 ₁′″, 2224 ₂′″, 2224 ₃′″ spaced by inactive areas 2228₁′″, 2228 ₂′″, 2228 ₃′″. While three active areas 2224′″ and threeinactive areas 2228′″ are illustrated, it is to be understood that moreor fewer such areas may be included.

By selectively activating electrode pairs, the actuator 2200′″ mayredistribute liquid dielectric 2212′″ to different regions of theinternal cavity 2209′″ of the shell 2208′″. For instance, displacing theliquid dielectric 2212′″ from one side of the internal cavity 2209′″ tothe other may cause the actuator 2200′″ to tilt (e.g., by displacingliquid dielectric from the active areas 2224 ₁′″ into the inactive areas2228 and the active areas 2224 ₂′″, 2224 ₃′″). This tilting mechanismcan be tuned by precise activation of the electrode pairs, for example.For example, FIG. 13B shows a rest state for the specific implementationhaving three electrode pairs. As illustrated in FIG. 13D, charging agiven pair of electrodes (e.g., electrodes 2216 ₁′″, 2217 ₁′″) causeslocal compression which results in an overall tilt of the actuator 2200′from the normal axis 2270′″. A high-voltage connection may be made withelectrode 2216 ₁′″ and a ground connection may be made with electrode2217 ₁′″. In some implementations, all electrode pairs can be activatedat once, causing a change in the overall thickness of the actuator2200′″. As illustrated in FIGS. 13C, 13E, and 13F, such donut type HASELactuators 2200′″ can be stacked into a stack 2600 to achieve furtherdegrees of three-dimensional mobility. For example, as illustrated bythe cross-section of the actuated stack 2600 shown in FIG. 13F,electrical connections can be routed through the center of the stack2600. Again, different modes of actuation can be achieved by varyingmaterial selection and geometry, and/or other properties.

FIG. 14A illustrates a representative process for measuring closed loopelectromechanical efficiency of HASEL actuators (e.g., donut-typeactuators 2200). FIG. 14B illustrates a representative experimentalsetup for measuring efficiency. As shown, a high-speed camera was usedto record displacement, y(t) (e.g., change in thickness of the inactivearea 2228). A digital acquisition (DAQ) unit sent a control signal tothe HV-amplifier and recorded voltage, V(t), and current I(t).Electrical energy was calculated using voltage and current measurements.FIGS. 14C-14I graphically represent various electrical measurements forthe actuation cycle of FIG. 14A. In FIG. 14C, voltage was applied as asymmetric triangular pattern with maximum voltage of 21 kV and period of1.5 s. In FIGS. 14D-14E, a sudden increase in current and a change inthe slope of charge indicates pull-in transition of the donut HASELactuator. In FIG. 14F, total electrical energy consumed was 2.88 mJ. InFIGS. 14G-14I, time histories of mechanical variables during actuationwere recorded for the same cycle. Total mechanical work or energy outputwas 0.59 mJ. Electromechanical efficiency for the cycle was 21%.

With reference now to FIGS. 15A-15C, an exemplary structure of azipper-HASEL actuator is shown. “Zipper-HASEL actuator” may refer to anyactuator described herein which is outfitted with a zipping orzipper-like mechanism as described below. This type of actuator utilizesan electrostatic zipping mechanism to enable lower voltage operation andmitigate pull-in instabilities.

A flexible shell or pouch 3604 (e.g., inextensible and/or elasticallydeformable) defines an enclosed internal cavity designed with one ormore tapered boundaries and that is filled with a liquid dielectric3606. A first electrode 3602 a is disposed over a first side of theenclosed internal cavity and a second electrode 3602 b is disposed overa second side of the enclosed internal cavity opposite the first side.The electrodes 3602 a, 3602 b are placed on opposing sides of a taperedboundary of the shell 3604, extending to or almost to the end of thetapered boundary.

In some embodiments, an edge of each of the electrodes 3602 a, 3602 b isflush or nearly flush with an edge of the enclosed internal cavitycontaining the liquid dielectric 3606. This geometry forms a zippinginitiation site 3600 wherein the opposing electrodes 3602 a, 3602 b arein close proximity to one another, whereas the electrodes 3602 a, 3602 bare separated by a greater distance toward the opposite end of theelectrodes. For example, as shown in FIG. 15A, at first reference point3612 along reference axis 3610, electrodes 3602 a and 3602 b areseparated by a greater distance than at second reference point 3614which is disposed nearer a peripheral edge of the shell 3604 than thefirst reference point. However, in some embodiments, such as those shownin FIGS. 16A-16C, the first reference point (where the distance betweenelectrodes is greater) may be disposed nearer the peripheral edge.

FIG. 15A illustrates the actuator at rest moments before or simultaneouswith application of voltage V₁. In this state, the electric fieldgenerated by the relatively low voltage is concentrated at the edge ofthe tapered boundary where the electrodes 3602 a, 3602 b are closesttogether. This causes the tapered region to experience a highelectrostatic stress in comparison to the rest of the shell 3604, and inresponse, the electrodes 3602 a, 3602 b move closer together.

As shown in FIG. 15B, as voltage is increased to V₂, the electrostaticforces 3630 extend further in a direction parallel to reference axis3620, causing a larger portion of the electrodes 3602 a, 3602 b to bedrawn together as the voltage overcomes the larger distances between theelectrodes through the liquid dielectric 3606. This urges the top andbottom layers of the shell to be urged together in opposing directionsparallel to reference axis 3620 by the electrodes and forces the liquiddielectric 3606 into the inactive area 3622 of the shell 3604 from theprogressive zipping site 3608 which moves progressively to the right inthe figure, through the active area 3624 as the voltage is increasedfurther. It should be appreciated that in the case of a strain limitinglayer, or when one side of the shell is otherwise fixed in position toanother object (e.g., another actuator or a solid surface), that oneside may remain stationary and relative movement between the top andbottom layers of the shell may be only with respect to the side which isnot fixed.

Notably, the length of the portion of electrodes 3602 a, 3602 b whichare fully drawn together can be controlled along a continuum from zeroto the full length of the electrodes based on how much voltage issupplied. This provides a high degree of control over the extent towhich the actuator is actuated as compared to binary or “on/off”actuators.

Upon full actuation caused by voltage V₃, shown in FIG. 15C,substantially all of the liquid dielectric 3606 is forced into theinactive region of shell 3604. In this state, electrodes 3602 a, 3602 bare fully drawn together, pinching the active portion of shell 3604. Inthis fully actuated state, the distance between the electrodes 3602 a,3602 b is constant along reference axis 3610 from first reference point3612 to second reference point 3614.

In the intermediate state shown in FIG. 15B, voltage V₂ is sufficient todraw the electrodes 3602 a, 3602 b together between second referencepoint 3614 and third reference point 3616. However, voltage V₂ may beinsufficient to overcome the increased pressure in shell 3604 (ascompared to the resting state shown in FIG. 36A) and close the gapbetween third reference point 3616 and fourth reference point 3618.However, increasing the voltage to V₃ may overcome the increasedpressure and draw the entirety of electrodes 3602 a, 3602 b together asshown in FIG. 15C. It should be noted that embodiments using aninextensible shell 3604 would experience a contraction in a directionalong reference axis 3610 in response to the vertical flexing of theshell 3604 caused by the increased pressure. In the embodimentillustrated in FIGS. 15A-15C, the shell 3604 is elastically deformable.

FIGS. 16A-16C illustrate toroidal or donut-shaped HASEL actuators asdescribed above in relation to FIGS. 8A-8E, for example, but withspecific attention to a zipping feature. FIG. 16A demonstrates theprogressive zipping phenomenon. As a low voltage V₁ is first applied,the electrodes are drawn together at zipping initiation site 3900, whichis in the center of the active area (i.e., the region sandwiched betweenthe electrodes) of the actuator. As the voltage is increased to V₂, andthen further to V₃, the progressive zipping locations 3902 move outwardin a ring-shape, forcing substantially all of the liquid dielectric intothe inactive area (i.e., the region outside the electrodes). FIGS. 16Band 16C show two design variations of toroidal zipper-HASEL actuators.In FIG. 16B, the zipping actuation begins from a central point 3903 ofactive area 3904 where the top layer and bottom layer of the shellmaterial is bonded together and actuation moves outward forcing theliquid dielectric into inactive area 3905 which surrounds active area3904. Electrostatic forces between the electrodes (covering active area3904 from top and bottom sides) upon application of voltage draws theelectrodes toward each other, displacing liquid dielectric from theactive area 3904 into the inactive area 3905. Because the top and bottomlayers of the shell are bonded at this central point 3903, that is wherethe layers are closest together and less electrostatic force is neededto draw the electrodes together. Hence, this is the location at whichthe zipping initiates. The drawing together of the electrodes forces theliquid dielectric outward in all radial directions.

In the embodiment of FIG. 16C, the zipping initiates along lines wherethe shell is bonded. FIG. 16D shows a representative data set ofactuation strain as a function of voltage under various loads for anactuator similar to the embodiment depicted in FIG. 16C. Notably, theactuator is capable of operating at 3 kV while limiting signs of pull-ininstabilities. The progressive zipping of the electrodes inhibits adiscontinuous jump in actuation strain, enabling precise control of thedeformation state of the actuator with the input voltage.

It should also be appreciated that, although not illustrated, actuatorssimilar to those shown and described in relation to FIGS. 16A-16C may beconstructed with the inactive are in the center, the inactive area beingsurrounded by an active area. For example, the first and secondelectrodes may be annular.

FIGS. 17A-17C illustrate various geometric considerations of azipper-HASEL actuator. FIG. 17A specifically illustrates a side view ofa peano-HASEL actuator shell in three phases: prior to actuation, duringactuation, and fully actuated. The shape of the shell is assumed to betwo intersecting circle segments beginning with radius r_(o) andtransitioning through various smaller radii as the zipping progresses.FIG. 17B models the total energy of the system as the sum of theelectrical potential energy of electrodes and the gravitationalpotential energy of a lifted mass. FIG. 17C provides an equation of thetotal energy of the system, parameterized by the angle, a, in the shell.

HASEL actuators which harness a zipping mechanism are advantageous forseveral reasons. For example, activation of the actuator begins at muchlower voltages than previously reported, since the electric field isinitially concentrated in a particular region of the shell. Further, theprogressive zipping actuation prevents instabilities within the softstructure, allowing for precise control of the deformation state viainput voltage. Further still, zipping mechanisms are easily incorporatedinto previous designs of HASEL but enable a multitude of new actuatordesigns facilitating various advantageous functions and motions.

FIGS. 18A-18B illustrate a pump 1800 having an expandable shell formedfrom a first flexible wall 1806 and a second flexible wall 1808. Betweenthe walls is a pump chamber 1804 having a first height 1816 whenactuators 1812 disposed therein are in an off-state with no voltageapplied to the system. Pump 1800 may be coupled with or integrallyformed with an inlet conduit 1828 and an outlet conduit 1830. One ormore check valves 1818, 1820 may be disposed between one or more ofconduits 1828, 1830 and pump chamber 1804. Actuators 1812 are donut-typeHASEL actuators as described above. When voltage is applied to the stackof actuators 1812, fluid inside the HASEL actuators is pushed to aperiphery, causing the height of the stack to expand in a y-directionthat is substantially perpendicular to a longitudinal axis 1854.Flexible walls 1806, 1808 may stretch to allow the pumps to expand inheight, thereby increasing the volume of pump chamber 1804 and drawingfluid through check valve 1818 in response to negative pressure. Whenthe voltage is removed from the system 1800, the actuators 1812 relax totheir original height 1816, and the elasticity of flexible walls 1806,1808 may apply a positive pressure to the fluid within chamber 1804 suchthat the fluid is displaced through second check valve 1820. In thisembodiment, the fluid being pumped flows through the chamber 1804 andaround the actuators 1812. As such, the fluid that can be pumped throughsuch a system may be limited to non-conductive fluid.

Referring now to FIGS. 19A-19C, a pumping system 1900 is shown. Thepumping system includes some components similar to those described withrespect to pumping system 300 in FIGS. 3A-3C. Like reference numberswill be used to identify like structures. System 1900 includes a pump1902 that may be in fluid communication with an inlet conduit 328 and anoutlet conduit 330. Pump 1902 includes at least one actuator housing 310separated from a pump chamber 304 by a first wall 306. First wall 306may be flexible, stretchable or otherwise movable by one or moreactuators 1912. Actuators 1912 may be linearly contracting HASELactuators. In contrast to the expanding actuators previously discussed,the linearly contracting actuators 1912 decrease in height in they-direction when a voltage is applied as shown in FIG. 19B. In anon-state, the contracted actuators 1912 pull the first wall 306 awayfrom the pump chamber 304, thereby increasing pump chamber height from afirst height 316 to a second height 1916, as shown in FIG. 19B. Thechange in pump chamber dimension creates negative pressure which drawsfluid into the pump chamber through a first check valve 318. Whenvoltage is removed from the system, the actuators 1912 return to theirelongated, off-state position and allow first wall 306 to apply positivepressure to the fluid within chamber 304. The positive pressuredisplaces fluid from the pump chamber 304 through second check valve 320into outlet conduit 330 as shown in FIG. 19C.

FIGS. 20A-20D show an embodiment of a HASEL actuator 2000. The actuatorincludes a dielectric film pouch 2002 filled with a fluid dielectric2004. Two electrodes 2006, 2008 are disposed on the outside of thedielectric film pouch 2002. A first electrode 2006 may be positionedsubstantially opposite second electrode 2008 as shown. FIGS. 20A, 20Bshow the actuator 2000 in an off-state. In the off-state, no voltage isapplied to the actuator and the electrodes 2006, 2008 generally conformto the resting shape of the pouch 2002. The pouch 2002 may be sandwichedbetween rigid plates 2010 to apply a load F to the actuator 2000. FIGS.20C, 20D show the actuator 2000 in an on-state. Voltage is applied toone of electrodes 2006 and 2008 causing the two electrodes to drawtogether. The electrodes draw together, or zip together, starting at theends of the electrodes that are nearest each other and draw closer alongthe length. As the electrodes pull together, dielectric fluid 2004 isdisplaced toward one side of the pouch 2002 causing the pouch to form amore circular or bulbous pocket at one end. The height of the actuatedpouch is shown as y in FIG. 20C; on-state height y is greater than theoff-state height, or initial height, y₀ shown in FIG. 20B. The on-stateheight y may be a function of the load F applied to the actuator via theplate 2010 and the applied voltage. These factors may determine a lengthz of the electrodes that zip together, and correspondingly, how muchdielectric fluid is displaced. Force per area for the system illustratedin FIGS. 20A-20D may be governed by Equation 1 below; height y for thesystem illustrated in FIGS. 20A-20D may be governed by Equation 2 below.

$\begin{matrix}{\frac{F}{LW} = {\frac{1}{L}\frac{\varepsilon_{0}\varepsilon_{r}}{4t}{{\Phi^{2}\left( {\frac{A}{y^{2}} - \frac{\pi}{4}} \right)}.}}} & {{Equation}1}\end{matrix}$ $\begin{matrix}{y = {L{{\frac{2}{\pi}\left\lbrack {1 - \frac{z}{L} - \sqrt{\left( {1 - \frac{z}{L}} \right)^{2} - {\pi\frac{A}{L^{2}}}}} \right\rbrack}.}}} & {{Equation}2}\end{matrix}$

FIG. 21 shows modeled and experimental data for the expanding HASELactuator 2000. The top left graph shows actuation pressure as a functionof pouch length for a variety of fill volumes. The top right graph showsmaximum change in height, also referred to as stroke, as a function ofpouch length for a variety of fill volumes. The bottom left graph showsactuation pressure as a function of stroke for a variety of pouch sizes.The bottom right graph shows actuation pressure as a function of strokefor a variety of fill volumes.

FIGS. 22A-22D show a diaphragm pump 2012 which uses actuator 2000 tocontrol fluid flow. Pump 2012 includes actuator 2000 having a flexibledielectric film pouch 2002 filled with dielectric fluid 2004. First andsecond flexible electrodes 2006, 2008 are disposed on the outside of thepouch 2002 as discussed with respect to FIGS. 20A-20D. The pump 2012further includes a housing 2022 having a cavity, in which actuator 2000is disposed, and a chamber 2016 which is separated from the actuator2000 by a diaphragm 2014. Chamber 2016 is fluidly coupled with an inletchannel 2028 and an outlet channel 2030 which may also be disposedwithin the pump housing 2022. A first one-way valve 2018 is disposedbetween inlet channel 2028 and chamber 2016; a second one-way valve 2020is disposed between chamber 2016 and outlet channel 2030.

Actuation of pump 2012 is shown in FIGS. 22C-22D. Referring to FIG. 22C,a first step of actuating pump 2012 is shown in the top left figure.Voltage is applied to actuator 2000 via electrode 2006. Electrodes 2006,2008 zip together along at least a portion of their lengths, therebypushing dielectric fluid 2004 away from the electrodes to form a morecircular or bulbous pocket having an increased height compared with theoff-state. The pocket engages diaphragm 2014 and pushes the diaphragminto chamber 2016. Fluid occupying chamber 2016 is pressurized due tothe membrane taking up more volume within the chamber 2016 as morevoltage is applied to the actuator. Once a first threshold pressure (forexample a pressure greater than pressure of fluid in the outlet channel2030) is reached, as shown in the top right figure, one-way valve 2020unseats from the pump housing 2022 and allows fluid to pass from thechamber 2016 into the outlet channel 2030. At the bottom right figure,applied voltage is decreased and dielectric fluid 2004 flows back towardthe electrodes thereby reducing height of the actuator and reducingpressure in chamber 2016. Once the pressure within chamber 2016 dropsbelow a second threshold pressure (for example, the pressure of fluid inthe inlet channel 2028), one-way valve unseats from the pump housing2022 and allows fluid to flow from inlet channel 2028 into chamber 2016.This final step is shown in the bottom left figure.

FIG. 22D shows pressure in chamber 2016 as a function of volume changeof chamber 2016 for each of the steps in the four-step pumping cycledescribed in FIG. 22C. Data is shown for both gas and liquid fluids. Foran incompressible fluid, the path from state 1 to state 2 is a verticalline because the incompressibility of the fluid prevents deformation ofthe diaphragm, until the outlet valve opens (state 2) and the fluid canflow out of the chamber at constant pressure (state 2 to 3). The maximumvolume (state 3) is limited by either the volume of the chamber 2016(i.e., all fluid is pumped out of the chamber) or by the strength of theactuator at the voltage F3, which is the difference of the force exertedby the HASEL actuator and the force required to deform the diaphragmsdivided by the area of the diaphragm (the curveP_(actuator)-P_(diaphragm)). For an incompressible fluid, the path fromstate 3 to 4 is again a vertical line. When the inlet valve is openliquid flows into the chamber at constant pressure (state 4 to 1) untilthe pump reaches state 1.

For a compressible fluid, the volume of the chamber changes when thefluid is pressurized. In the pressure-volume plane, the process ofpressurization is represented by a curved line from state 1 to state 2′,the shape of which is determined by the behavior of the fluid (e.g.,ideal gas law). The pumping phase for a compressible fluid follows thehorizontal line from state 2′ to state 3. During depressurization, acompressible fluid will expand before pressure in the chamber is lowenough to cause the inlet valve to open (state 4′). This transition isagain determined by the compressibility of the fluid within the chamberand is represented by the curved line from state 3 to state 4′ in thepressure-volume plane. When the inlet valve is open, fluid flows intothe chamber at constant pressure (state 4 to 1) until state 1 isreached.

The area enclosed by the loops 1-2-3-4 and 1-2′-3-4′ represent themechanical work output during one pumping cycle for an incompressibleand a compressible fluid, respectively. More work per cycle is expectedwhen pumping incompressible fluids such as water than when pumping acompressible fluid such as air. When pumping compressible fluids, theshape of paths from 1 to 2′ and 3 to 4′ depends on the ratio of thevolumes of states 1 and 2′, and the ratio of the volumes of state 3 and4′. Reducing the amount of dead space within the pump chamber willincrease the slope of the paths from 1 to 2′ and 3 to 4′, which willresult in more work per cycle when pumping a compressible fluid.Ultimately the work per cycle for the pump may be limited by theperformance of the HASEL actuator (state 3).

FIGS. 23A and 23B show an exploded view and a cross-sectional view,respectively, of pump 2012.

FIG. 24A shows a top down and cross-sectional views of an exampleone-way valve that can be used within pump 2012. The one-way valve maybe a tethered-plate style valve layer within the pump 2012. Exampledimensions are provided; however, other sizes and configurations arepossible without departing from the scope of the present disclosure.FIG. 24B shows forward flow rate as a function of pressure for the valveshown in FIG. 24A. In this particular example, the valve may begin toopen and flow rate therethrough increases when pressure reaches 0.1 kPa.FIG. 24C measures reverse flow rate as a function of pressure. In thisexample, flow rate increases until reverse pressure reaches 0.1 kPa, atwhich point, the valve closes or substantially closes.

FIGS. 25A-25H show experimental set-up and results for various testingperformance of pump 2012 when pumping air. FIG. 25A shows theexperimental set-up for measuring blocked pressure by connecting theoutlet of the pump directly to a pressure sensor. Data for blockedpressure as a function of applied voltage and blocked pressure as afunction of frequency is shown in FIGS. 25B, 25C, respectively. FIG. 25Dshows the experimental set-up for measuring flow rate by connecting aflow meter to the pump outlet and opening the pump outlet to atmosphere.Data for average and maximum flow as a function of applied voltage andaverage and maximum flow as a function of frequency is shown in FIGS.25E, 25F, respectively. FIG. 25G shows the experimental set-up formeasuring flow rate as a function of pressure by attaching the outletpump to an inflatable membrane. FIG. 25H shows a graph of average flowrate and average power as a function of pressure.

FIGS. 26A-26D relate to the experimental set-up and results for testingperformance of pump 2012 when pumping water. FIG. 26A shows blockedpressure as a function of applied voltage. FIG. 26B shows blockedpressure as a function of frequency. FIG. 26C shows the equipment set-upfor testing average flow and average power as a function of pressure.These variables were measured by attaching the pump inlet to alarge-diameter reservoir and the outlet to a small-diameter reservoir.Average flow and average power as a function of pressure are shown inFIG. 26D.

FIG. 27 illustrates the performance of pump 2012 when pumping air andwhen pumping liquid in comparison to other types of pumps. Specifically,comparisons of free flow rate and blocked pressure are shown.

FIG. 28 illustrates an example actuation signal used to supply voltageto the pump 2012. The actuation signal can be a reversing polarity sinewave having a peak-to-peak voltage magnitude of Φ with an offset of Φ/2.The polarity of the sine wave may switch after every period, T, toreduce effects of charge retention. Other actuation signals are alsopossible such as square waves, ramped square waves, and triangularwaves.

FIGS. 29A-29C show a system 2900 having a pump 2012 that powers anartificial muscle 2902. FIG. 29A shows a photograph of the system atrest and during actuation. The system includes a weight 2904 coupled tothe artificial muscle 2902 for use in testing performance of the systemunder different loading conditions. FIG. 29B shows the actuation stroke,or change in length, of the artificial muscle 2902 as a function of timefor various loading conditions. Applied voltage to the system for thistest was 6 kV and frequency was 10 Hz, though other values are possibleto obtain different results. FIG. 29C shows load as a function of strainfor the artificial muscle.

Referring to FIGS. 30A-30D, a pumping system 3000 is illustrated. Thepumping system 3000 includes a pump chamber 3004 defined by a first wall3006 and a second wall 3008 and having an inlet region 3028 and anoutlet region 3030. The first wall 3006 may comprise a surface of aflexible electrode 3014, as shown or may be a separate flexible wallcomponent. The second wall 3008 may be a rigid or semi-rigid component.The pump chamber 3004 has a first height dimension 3016 in an off-stateas shown in FIG. 30A. The pump chamber 3004 is configured to receive avolume of fluid 3026, which may be any type of fluid including gases orliquids having conductive, dielectric, or insulative properties.

Moving the volume of fluid 3026 through the pumping system 3000 may beaccomplished by selectively actuating at least two of a plurality ofdistinct electrodes 3012 a-3012 h to form one or more dielectric fluidpockets 3058 by selectively moving dielectric fluid volume 3024. Forexample, referring to FIG. 30B, a pocket 3058 of dielectric fluid isformed by applying voltage, V, to spaced apart or non-adjacentelectrodes 3012 a and 3012 d. When the voltage is applied, first andsecond electric fields 3032 a, 3032 b are generated by the firstdielectric 3010 on which the electrodes are disposed. The electricfields interact with the flexible electrode 3014, causing at least afirst and second portion 3018, 3020 of the flexible electrode 3014 tomove toward the first dielectric 3010 and displace dielectric fluid toform the pocket 3058. Electrodes 3012 b, 3012 c between the energizedelectrodes 3012 a, 3012 d do not receive voltage in order to facilitatebending of the flexible electrode 3014 away from the electrodes 3012 b,3012 c to form the pocket 3058. The first dielectric 3010 may be a rigidor semi-rigid material such as biaxially oriented polyester film,biaxially oriented polypropylene, polyvinylidene fluoride terpolymer,and polyimide film. A second dielectric 3034 formed from a flexible orstretchable material may be included between the dielectric fluid volume3024 and flexible electrode 3014 as shown, but is not required in allembodiments.

Formation of the pocket 3058 at least partially decreases the height3016 of the pump chamber 3004 to moderate flow of the volume of fluid3026 through the pumping system 3000. In the example shown in FIG. 30B,the height of the pocket 3058 is equal to the first height dimension3016 of pumping chamber 3004 such that the pump chamber 3004 is occludedat the pocket 3058; however, many variations are possible. For example,several smaller pockets may be formed by actuating every other, everythird, every fourth, etc. of the plurality of distinct electrodes. Insome embodiments, the dielectric fluid volume 3024 may be in fluidcommunication with a reservoir (not shown) having a reserve volume ofdielectric fluid that can be moved into the pumping system 3000 in orderto facilitate generating several large pockets of dielectric fluidwithin the pumping system. Alternatively, a portion of the dielectricfluid volume 3024 may be moved out of pumping system 3000 to increase aheight 3016 of pump chamber 3004 and/or decrease the number or size ofpockets 358 and/or allow increased fluid flow through the pumping system3000. Thus, the operation of pumping system 3000 can be adjusted andmodified using a variety of design variations including amount ofdielectric fluid included in the pumping system, initial height of pumpchamber 3004, amount of voltage V, applied to one or more of electrodes3012 a-312 h, and sequence of applying voltage V to the one or moreelectrodes.

Referring to FIG. 30C, an example of moving the pocket 3058, and thuspumping the fluid volume 3026, is shown. To move the pocket from thelocation shown in FIG. 30B to the location shown in FIG. 30C, voltageVis applied to electrode 3012 b and 3012 c and voltage is withdrawn fromelectrodes 3012 d, 3012 e. As the flexible electrode 3014 draws closerto the electrodes 3012 b, 3012 c, dielectric fluid is displaced towardthe electrodes 3012 d, 3012 e which are not actively generating anelectric field. Thus, by selectively applying voltage to spaced apart ornon-adjacent distinct electrodes, the pocket 3058 can move along alength of the pumping system 3000 applying positive pressure to a firstportion of fluid 3026 a (i.e., the portion of fluid to the right of themoving pocket) and applying a negative pressure to a second portion offluid 3026 b (i.e., the portion of fluid to the left of the movingpocket).

In some embodiments, it may be advantageous to keep the size of pocket3058 substantially constant during the pumping operation. For example,when operating the pumping system 3000 as a peristaltic pump, it may beadvantageous to keep volume 3026 a separate from volume 3026 b bymaintaining the occlusion of pump chamber 3004 with pocket 3058. One wayto achieve such operation is to keep constant the number of electrodesthat do not receive voltage. For example, in both of the states shown inFIGS. 30B and 30C, there are two electrodes that do not receive voltage.At a first time, when electrode 3012 b receives voltage, voltage issimultaneously withdrawn from electrode 3012 d. This transition mayinclude abruptly applying/removing voltage from the respectiveelectrodes or may include tapering or transitioning the voltageapplication/removal for smoother movement of the pocket. At a secondtime, when electrode 3012 c receives voltage, voltage is simultaneouslywithdrawn from electrode 3012 e. As discussed above, this transition mayinclude abruptly applying/removing voltage from the respectiveelectrodes or may include tapering or transitioning the voltageapplication/removal. In this way, dimensions of pocket 3058 aresubstantially constant as the pocket gradually moves along a length ofthe pumping system 3000 to direct fluid 3026.

Referring to FIGS. 31A-31C, a pumping system 3100 is shown havingcomponents similar to those described with respect to FIGS. 30A-30C.Like components are labeled with like reference numbers for simplicity.The function of pumping system 3100 is similar to that of pumping system3000; however, pumping system 3100 includes an opening 3062 in thesecond wall 3008 where fluid 3026 may exit pump chamber 3004. As pocket3058 approaches the opening 3062, positive pressure applied to the firstportion of fluid 3026 a may cause the first portion of fluid 3026 a toexit the pump chamber 3004 through the opening 3062. The amount of fluiddisplaced through opening 3062 and/or the pressure of that fluid may beadjusted by changing the size of opening 3062, changing the size of theoutlet region 3030, and/or changing the speed at which pocket 3058approaches the opening 3062. Many variations are possible withoutdeparting from the scope of the present application.

Once the pocket 3058 reaches the opening 3062 (FIG. 31C), the openingmay be occluded by a portion of the pocket such that first and secondportions of fluid 3026 a, 3026 b are prevented from exiting the pumpchamber 3004 through opening 3062. While one opening is show in thepumping system 3100, multiple openings may be included which may beselectively occluded by one or more pocket 3058. In some embodiments, acheck valve (not shown) may be included within the opening 3062 tofurther control fluid flow through the pumping system 3100.

While the pumping systems 3000, 3100 are shown in a linearconfiguration, many shapes are possible. For example, the pumpingsystems 3000, 3100 may be configured in an arc, s-shape, ring, or othercontinuous or non-continuous shape. Additionally, while eight electrodes3012 are shown, more or fewer electrodes may be included along thelength of the pumping system. Spacing between the electrodes may beselected such that when an electrode receives an applied voltage, thestrength of the resulting electric field does not exceed the dielectricstrength of an encapsulation layer 3060 surrounding and separating eachelectrode. Encapsulation layer 3060 may be a dielectric layer separatefrom the first dielectric 3010; alternatively, electrodes 3012 may beincluded in the first dielectric 3010 such that the first dielectric3010 forms the encapsulation layer.

In pumping system 3000, 3100, voltage is delivered to the plurality ofelectrodes 3012 by a power source (not shown). A control module may beoperably coupled to the power source to provide switching and voltageapplication instruction for each of the plurality of electrodes.Feedback mechanisms similar to those described with respect to FIG. 7may be implemented to detect various flow and pressure characteristicsof fluid within the pump chamber.

The foregoing describes embodiments of the present invention and is notto be construed as limiting thereof. Although a few exemplaryembodiments of this invention have been described, those skilled in theart will readily appreciate that many modifications are possible in theexemplary embodiments without materially departing from the novelteachings and advantages of this invention. For example, many of thepumping systems may be modified to include different types, numbers, andarrangements of actuators. The actuators may be operated in various waysto achieve different results.

Many aspects of the invention are described in the present disclosure.

In a first aspect, a method of pumping fluid is disclosed. The methodincludes providing a first pump comprising a first actuator chamber thatincludes at least a first actuator. The pump further includes a firstpump chamber and a first flexible diaphragm coupled with the firstactuator and separating the first actuator chamber from the first pumpchamber. The method further includes electrically actuating the firstactuator to move the first flexible diaphragm and applying pressure to afluid disposed in the first pump chamber.

In a second aspect, the first actuator comprises an expanding actuatorconfigured to expand the first flexible diaphragm into the first pumpchamber.

In a third aspect, applying pressure to the fluid comprises applying apositive pressure.

In a fourth aspect, the first actuator comprises a contracting actuatorconfigured to contract the first flexible diaphragm into the firstactuator chamber.

In a fifth aspect, applying pressure to the fluid comprises applying anegative pressure.

In a sixth aspect, electrically actuating the first actuator comprisesmodulating an amount of voltage applied to the first actuator toselectively adjust an amount of movement of the first actuator.

In a seventh aspect, electrically actuating the first actuator comprisesapplying a voltage to at least one of a first electrode on a first sideof a flexible membrane pouch and a second electrode on a second side ofthe flexible membrane pouch, wherein the flexible membrane pouchencloses a dielectric fluid. The method further comprises in an onstate, generating an electric field to cause the first electrode and thesecond electrode to move toward each other; displacing a portion of thedielectric fluid between the first electrode and the second electrode;and changing at least a height dimension of the first actuator by aselected amount.

In an eight aspect, the height dimension of the first actuator increasesin the on state.

In a ninth aspect, the method further comprises providing a second pumpin series with the first pump. The second pump comprises a secondactuator chamber comprising at least a second actuator, a second pumpchamber, and a second flexible diaphragm coupled with the secondactuator and separating the first actuator chamber from the second pumpchamber, wherein the second pump chamber is fluidly coupled with thefirst pump chamber. The method further comprises electrically actuatingthe second actuator to move the second flexible diaphragm and applyingpressure to a fluid disposed in the second pump chamber.

In a tenth aspect, the first pump is electrically actuated at a firsttime and the second pump is electrically actuated at a second timedifferent from the first time.

In an eleventh aspect, the first flexible diaphragm is coupled with thesecond flexible diaphragm.

In a twelfth aspect, a pump includes a pump chamber comprising a firstwall, a first dielectric adjacent the first wall, a first electrodeelectrically coupled with the first dielectric, and a second electrodecomprising a first end coupled with the first wall of the pump chamberand a second end coupled with a second wall of the pump chamber, whereinthe second electrode is flexible between the first and second ends, andwherein the second electrode separates a first volume of fluid from asecond volume of fluid.

In a thirteenth aspect, the first dielectric is configured to generate afirst electric field in response to receiving voltage from the firstelectrode.

In a fourteenth aspect, at least a portion of the second electrode isconfigured to move toward the first dielectric in response to the firstelectric field.

In a fifteenth aspect, movement of the second electrode toward the firstdielectric is configured to apply positive pressure to the first volumeof fluid and negative pressure to the second volume of fluid.

In a sixteenth aspect, the first wall is substantially rigid.

In a seventeenth aspect, the first wall comprises a flexible membrane.

In an eighteenth aspect, the first wall comprises at least oneinsulating connector configured to couple with the first end of thesecond electrode.

In a nineteenth aspect, the pumping system further comprises a secondwall opposite the first wall; a second dielectric adjacent the secondwall of the pump chamber; and a third electrode electrically coupledwith the second dielectric.

In a twentieth aspect, the second dielectric is configured to generate asecond electric field in response to receiving voltage from the thirdelectrode.

In a twenty first aspect, at least a portion of the second electrode isconfigured to move toward the second dielectric in response the secondelectric field.

In a twenty second aspect, movement of the second electrode toward thesecond dielectric is configured to apply negative pressure to the firstvolume of fluid and positive pressure to the second volume of fluid.

In a twenty third aspect, the second wall is substantially rigid.

In a twenty fourth aspect, the system comprises at least two stablestates.

In a twenty fifth aspect, the first dielectric is selected from a groupconsisting of biaxially oriented polyester film, biaxially orientedpolypropylene, polyvinylidene fluoride terpolymer, and polyimide film.

In a twenty sixth aspect, the first electrode is selected from a groupconsisting of carbon grease, carbon ink, silver ink, conductive fabric,and conductive elastomer.

In a twenty seventh aspect, the first fluid and the second fluid areliquid dielectrics.

In a twenty eighth aspect, the liquid dielectrics are selected from agroup consisting of vegetable-based transformer oils and silicone-basedtransformer oils.

In a twenty ninth aspect, a pump includes a pump chamber comprising afirst wall and a second wall opposite the first wall; a first dielectricadjacent the first wall; a first electrode electrically coupled with thefirst dielectric; and a second electrode comprising a first end and asecond end, wherein the first and second ends are supported between thefirst wall and the second wall, wherein the second electrode is movablebetween the first and second ends, and wherein the second electrodeseparates a first volume of fluid from a second volume of fluid.

In a thirtieth aspect, the first dielectric is configured to generate afirst electric field in response to receiving a voltage from the firstelectrode.

In a thirty first aspect, a portion of the second electrode between thefirst and second ends is configured to move toward the first dielectricin response to the first electric field.

In a thirty second aspect, the first and second ends are supported on alongitudinal axis of the pump chamber.

In a thirty third aspect, the pump further includes a second dielectricadjacent the second wall; and a third electrode electrically coupledwith the second dielectric.

In a thirty fourth aspect, the second dielectric is configured togenerate a second electric field in response to receiving a voltage fromthe third electrode.

In a thirty fifth aspect, the portion of the second electrode betweenthe first and second ends is configured to move toward the seconddielectric in response to the second electric field.

In a thirty sixth aspect, the second electric field is configured to begenerated at a different time than the first electric field.

In a thirty seventh aspect, the pump comprises at least three stablestates.

In a thirty eighth aspect, a method of pumping fluid includes providinga first fluid in a first volume of a pump chamber; providing a secondfluid in a second volume of the pump chamber, wherein the first volumeis separated from the second volume by a movable electrode; providing afirst dielectric adjacent a first side of the pump chamber; generating afirst electric field by applying a first voltage to the firstdielectric; and moving at least a portion of the movable electrodetoward the first dielectric in response to the first electric field,wherein moving the movable electrode toward the first dielectric appliesa positive pressure to the first fluid in the first volume and anegative pressure to the second fluid in the second volume.

In a thirty ninth aspect, the movable electrode comprises a flexiblematerial.

In a fortieth aspect, the flexible material is selected from a groupconsisting of carbon grease, carbon ink, silver ink, conductive fabric,or conductive elastomer.

In a forty first aspect, the first and second fluids comprise the samefluid.

In a forty second aspect, the first and second fluids are selected froma group consisting of vegetable-based transformer oils andsilicone-based transformer oils.

In a forty third aspect, the method further includes providing a seconddielectric adjacent a second side of the pump chamber; generating asecond electric field by applying a second voltage to the seconddielectric; and moving at least a portion of the movable electrodetoward the second dielectric in response to the second electric field,wherein moving the movable electrode toward the second dielectricapplies a negative pressure to the first fluid in the first volume and apositive pressure to the second fluid in the second volume.

In a forty fourth aspect, the first electric field is generated at afirst time and the second electric field is generated at a second timedifferent from the first time.

In a forty fifth aspect, the first and second electric fields aregenerated at alternating times at a selected frequency.

In a forty sixth aspect, a pumping system includes a pump chamberdefined by a first wall comprising a flexible electrode and a secondwall. A first fluid occupies the pump chamber. A dielectric fluid isdisposed within a compartment defined by the flexible electrode and afirst dielectric. A plurality of separate electrodes are disposed on thefirst dielectric and each electrode is configured to selectively receivevoltage and generate an electric field in response to the appliedvoltage.

In a forty seventh aspect, a method of operating the pumping systemdescribed in the forty sixth aspect includes selectively applyingvoltage to at least two of the plurality of electrodes, wherein the twoof the plurality of electrodes are not adjacent. At least two electricfields are generated in response to applying voltage to at least two ofthe plurality of electrodes. At least a first and second portion of theflexible electrode are drawn toward the first dielectric in response tothe generated electric field, thereby displacing dielectric fluid into apocket and adjusting at least one of pressure and flow of the fluidoccupying the pump chamber.

Accordingly, many different embodiments stem from the above descriptionand the drawings. It will be understood that it would be undulyrepetitious and obfuscating to literally describe and illustrate everycombination and subcombination of these embodiments. As such, thepresent specification, including the drawings, shall be construed toconstitute a complete written description of all combinations andsubcombinations of the embodiments described herein, and of the mannerand process of making and using them, and shall support claims to anysuch combination or subcombination.

In the specification, there have been disclosed embodiments of theinvention and, although specific terms are employed, they are used in ageneric and descriptive sense only and not for purposes of limitation.Although a few exemplary embodiments of this invention have beendescribed, those skilled in the art will readily appreciate that manymodifications are possible in the exemplary embodiments withoutmaterially departing from the novel teachings and advantages of thisinvention. Accordingly, all such modifications are intended to beincluded within the scope of this invention as defined in the claims.Therefore, it is to be understood that the foregoing is illustrative ofthe present invention and is not to be construed as limited to thespecific embodiments disclosed, and that modifications to the disclosedembodiments, as well as other embodiments, are intended to be includedwithin the scope of the appended claims. The invention is defined by thefollowing claims, with equivalents of the claims to be included therein.

That which is claimed:
 1. A pumping system comprising: a conduit comprising an inlet region and an outlet region; a first pump coupled with the conduit between the inlet region and the outlet region, wherein the first pump comprises: a first actuator chamber configured to house at least a first actuator; a first pump chamber aligned along a longitudinal axis of the conduit, wherein the first pump chamber is in fluid communication with the inlet region and the outlet region; and a first flexible diaphragm separating the first actuator chamber from the first pump chamber.
 2. The pumping system of claim 1, wherein the first actuator is an expanding actuator configured to expand in a height direction substantially perpendicular to the longitudinal axis when the expanding actuator is electrically actuated, and wherein the first flexible diaphragm is configured to expand into the first pump chamber.
 3. The pumping system of claim 2, wherein the first flexible diaphragm is configured to expand by a distance less than or equal to a height of the first pump chamber.
 4. The pumping system of claim 2, wherein the expanding actuator has a first height associated with an off-state and a second height associated with an on-state, and wherein the second height is greater than the first height.
 5. The pumping system of claim 4, wherein a difference between the first height and the second height is less than the height of the first pump chamber.
 6. The pumping system of claim 2, wherein the expanding actuator comprises: a first flexible membrane pouch having a first electrode on a first side and a second electrode on a second side opposite the first side; and a first liquid dielectric within the first flexible membrane pouch, wherein the first electrode and the second electrode are configured to attract in response to a voltage applied to one of the first and second electrodes, and wherein the first liquid dielectric is configured to be displaced when the first and second electrodes attract.
 7. The pumping system of claim 6, further comprising at least two expanding actuators that are stacked along the height direction.
 8. The pumping system of claim 1, wherein the at least one actuator is a contracting actuator configured to contract in the height direction when the contracting actuator is electrically actuated, and wherein the first flexible diaphragm is configured to move into the first actuator chamber.
 9. The pumping system of claim 8, wherein the first flexible diaphragm is configured to increase a volume of the first pump chamber.
 10. The pumping system of claim 9, wherein the contracting actuator has a third height associated with an off-state and a fourth height associated with an on-state, and wherein the third height is greater than the fourth height.
 11. The pumping system of claim 10, wherein a difference between the third height and the fourth height is greater than the height of the first pump chamber.
 12. The pumping system of claim 10, wherein the contracting actuator comprises: a second flexible membrane pouch having a third electrode on a third side and a fourth electrode on a fourth side opposite the third side; and a second liquid dielectric within the second flexible membrane pouch, wherein the third electrode and the fourth electrode are configured to attract in response to an applied voltage associated with the on state, and wherein the second liquid dielectric is configured to be displaced when the third and fourth electrodes attract.
 13. The pumping system of claim 12, further comprising at least two contracting actuators stacked along the height direction.
 14. The pumping system of claim 12, wherein the first and second liquid dielectrics are selected from a group consisting of vegetable-based transformer oils and silicone-based transformer oils.
 15. The system of claim 1, wherein the pump further comprises: a second actuator chamber configured to house at least a second actuator; and a second flexible diaphragm separating the second actuator chamber from the first pump chamber.
 16. The system of claim 15, wherein the second actuator is a second expanding actuator configured to expand in the height when the second expanding actuator is electrically actuated.
 17. The pumping system of claim 15, wherein the second actuator is a second contracting actuator configured to contract in the height direction when the second contracting actuator is electrically actuated.
 18. The system of claim 1, further comprising a second pump coupled with the conduit between the first pump and the outlet region, wherein the second pump comprises: a third actuator chamber configured to house at least a third actuator; a second pump chamber aligned along the longitudinal axis of the conduit and the first pump chamber, wherein the second pump chamber is in fluid communication with the inlet region and the outlet region; and a third flexible diaphragm separating the third actuator chamber from the second pump chamber.
 19. The system of claim 18, wherein the first actuator is configured to be electrically actuated at a first time and the third actuator is configured to be electrically actuated at a second time.
 20. The pumping system of claim 1, further comprising at least one check valve disposed within the conduit. 